ALBERT

Description: In Nepal, forest management priority is shifting to scientific management from conventional management. Though, the forest officials claims that scientific management is beneficial to the forest user groups, comparative financial assessment with conventional management remains unexplored. Following a case study approach, this study compares financial efficiency of two forest management systems in the community forests, focusing on benefit-cost ratio. The study conducted documents review, focus group discussions, and rapid survey to quantify costs and benefits from each forest management system. Conventional management gave a higher benefit-cost ratio to the forest user groups, irrespective of whether forest products are sold at a subsidized price or par with the market price. However, scientific management required high forest management costs and thus had a lower benefit-cost ratio. Sensitivity analysis between two systems revealed that conventional management gave a higher benefit-cost ratio in all cases. The study concludes that forest user groups would bear financial loss if they do not fix the price of the timber at par with the market in scientific management, and in such a case, the tagged price will be beyond affordability of the forest users. Furthermore, scientific management has discouraged kind contribution of users in managing forest. Besides, social and environmental consequences of scientific management cannot be ignored. Hence, the study argues for reconsidering current scientific management considering likely economic and social consequences to the forest user groups.

Description: In this paper, we propose an innovative method for conventional triaxial tests of concrete with a confining cell. The polyvinyl chloride (PVC) pipe is used as a mould to cast concrete and also as a membrane to isolate the concrete specimen from oil under confinements. This method is termed as PMM (i.e., PVC pipe is used as a mould and membrane). However, a heat-shrink sleeve is used as a membrane in the traditional test method (TMM). Specimens were made from mortar without coarse aggregates in the present experiment. Under six confinements (0–70 MPa), the conventional triaxial compression tests were performed on ultrahigh-strength (150 MPa) and high-strength (82 MPa) mortar specimens by PMM and TMM. The results indicate the following: (i) there is a characteristic confinement p0; when the confinement is lower than p0, the strength by PMM is higher than that by TMM; on the contrary, when the confinement is higher than p0, the strengths by both methods are almost identical. In this work, p0 is between 0 and 5 MPa. (ii) When the confinement is 5–70 MPa, the relationship between the peak stress of high-strength mortar and confinement is characterized by a monotonically rising straight line; however, a monotonically rising upward convex curve describes the peak stress of ultrahigh-strength mortar related to the confinement. (iii) The residual strength using PMM is significantly higher than that using TMM at zero confinement or lower confinements, but the residual strengths by these two methods are approximately identical at higher confinements. (iv) The transverse cracks appear in the mortar specimen inside the PVC pipe after enduring a triaxial loading using PMM. However, there is no such phenomenon when TMM is applied.

Description: Chloride corrosion test was carried out in 4% NaCl solution to study the chloride corrosion resistance of rubber concrete. Rubber concrete was prepared by using 20 mesh, 1∼3 mm, and 3∼6 mm rubber particles instead of sand by 5%, 10%, 15%, and 20% of the cementitious material mass. The P-wave velocity and compressive strength of rubber concrete were measured. The microstructure of rubber concrete corroded by chloride was analyzed by SEM. The micromorphology was compared with the macrofailure characteristics under uniaxial compression. The results show that the rubber concrete was still in the early stage of erosion. With the increase of immersion time at the age of 110 days, the P-wave velocity and compressive strength of concrete were generally on the rise. Furthermore, during the period of erosion, the mechanical properties of rubber concrete increased with the increase of rubber particle size and decreased with the increase of the content. Therefore, when the rubber particle size was 3∼6 mm and the content was 5%, the antierosion performance was the best. This study has a certain guiding significance for the chloride corrosion resistance of rubber concrete.

Description: In this paper, an intelligent modeling approach is presented to predict the shear strength of the internal reinforced concrete (RC) beam-column joints and used to analyze the sensitivity of the influence factors on the shear strength. The proposed approach is established based on the famous boosting-family ensemble machine learning (ML) algorithms, i.e., gradient boosting regression tree (GBRT), which generates a strong predictive model by integrating several weak predictors, which are obtained by the well-known individual ML algorithms, e.g., DT, ANN, and SVM. The strong model is boosted as each weak predictor has its own weight in the final combination according to the performance. Compared with the conventional mechanical-driven shear strength models, e.g., the well-known modified compression field theory (MCFT), the proposed model can avoid the complicated derivation process of shear mechanism and calibration of the involved empirical parameters; thus, it provides a more convenient, fast, and robust alternative way for predicting the shear strength of the internal RC joints. To train and test the GBRT model, a total of 86 internal RC joint specimens are collected from the literatures, and four traditional ML models and the MCFT model are also employed as comparisons. The results indicate that the GBRT model is superior to both the traditional ML models and MCFT model, as its degree-of-fitting is the highest and the predicting dispersion is the lowest. Finally, the model is used to investigate the influences of different parameters on the shear strength of the internal RC joint, and the sensitivity and importance of the corresponding parameters are obtained.

Description: The fracture development and distribution around the deep soft rock roadway are pivotal to any underground design. In this paper, both field investigation and numerical simulation were taken to study the fracture evolution and rock deformation of a coal mine roadway at Kouzidong mine, Fuyang, Anhui Province, China. Based on the borehole imaging technique, we found an asymmetric distribution of the fracture zone in the surrounding rock of the roadway. By analyzing the C value of the fractures in the borehole images,we found that the fracture interval distribution of the surrounding rock of the tunnel, the number of fractures will fluctuate decrease with the increase of the depth. To effectively study the fracture propagation and distribution of the roadway under longwall retreatment and roadway excavation, the global-local numerical technique was applied via FLAC3D and PFC2D. In the roadway excavation process, fractures were first formed in the shallow section of the roadway and progressively propagated toward the deeper soft rock layer; the main failure mechanism was a tensile failure. During longwall retreatment, fractures continuously developed toward the deeper soft rock layer. However, the failure mechanism transformed to shear failure. From numerical results, it can be seen that the stress concentration at the ribs was released, which led to shear failure at the roof and floor. Due to the extensive tensile cracks in the shallow section, the surrounding rock experienced expansion and fracture. The deep shear failure also induced the formation of the nonadjacent crushing zone and elastic zone, which is in line with the borehole imaging results.

Description: Silty sand is highly permeable and has a large internal friction angle. To ensure the stable and efficient construction of the Earth pressure balance (EPB) shield in silt stratum, it is necessary to reduce the disturbance to the stratum during tunneling and reduce the risk of spewing and blocking during soil discharge. Thus, a new type of dense slurry-EPB shield construction technology is proposed. Using a custom-made test device, the consolidation tests were conducted on sand after mixing it with different amounts of slurry to study the change in the pore pressure in the mixed soil and sand stratum and analyze the stress transmission rule. In addition, slump tests were conducted on the mixed soil to study the change in the fluidity. Based on the laboratory test results, a field investigation was carried out to study the effects of the amount of slurry addition on the pore pressure in the stratum, the driving parameters, and the sand’s flowability during shield tunneling. The results show that when the amount of slurry reaches a certain value, the filter cake effect occurs. The greater the amount of slurry added during the shield tunneling, the smaller the rate of change of the pore pressure in the stratum. When the amount of BC2 slurry added reached 8 m3 per ring, the rate of change was reduced by 57%, and the slump value improved by 93%. The type of filter cake of the DS-EPB shield was only internal filter cake during tunneling, which reduced the disturbance of the excavation face and improved the flowability of the sand. These results are of great significance to the application and promotion of DS-EPB shields in sandy cobble strata.

Description: An assessment of uncertainty in flood hydrograph features, e.g., peak discharge and flood volume due to variability in the rainfall-runoff model (HEC-HMS) parameters and rainfall characteristics, e.g., depth and duration, is conducted. Flood hydrographs are generated using a rain pattern generator (RPG) and HEC-HMS models through Monte Carlo simulation considering uncertainty in stochastic variables. The uncertainties in HEC-HMS parameters (e.g., loss, base flow, and unit hydrograph) are estimated using their probability distribution functions. The flood events are obtained by simulating runoff for rainfall events using the generated model parameters. The uncertainties due to rainfall and model parameters on generated flood hydrographs are evaluated using the relative coefficient of variation (RCV). The results reveal a higher RCV index for flood volume (RCV = 153) than peak discharge (RCV = 116) for a 12-hr rainfall duration. The average relative RCV (ARRCV) index computed for hydrological component (e.g., base flow, loss, or unit hydrograph) indicates the highest impact of rainfall depth on flood volume and peak. The results indicate that rainfall depth is the main source of uncertainty of flood peak and volume.

Description: The study of rock blasting failure pattern is of engineering importance. In order to investigate rock blasting failure pattern with one free boundary, high-speed photography technology is introduced into the two-dimensional granite model. Through high-speed camera images, a crack that originated from spalling is observed and then propagates inward. By using the high-speed digital image correlation method, the full-strain fields on the surface of the specimens are calculated. The preliminary results show that von Mises strain localization appears on the specimen surface near the free boundary. The axial strains near that crack present three kinds of characteristics. There are the joint action areas of the strain localization by analyzing strains in different directions, and the strain localizations are related to the crack propagation. Ultimately, after analysis of the experimental results, the preliminary diagrammatic drawing of rock blasting failure pattern under stress wave action with one free boundary is drawn.

Description: The rock and soil on the shore of the bank are unsteady and slide in a poor environment, affecting the water body in the river channel and forming landslide-generated tsunamis. This directly impacts the navigation of vessels in the river. In this study, the river course and sailing ships in the Wanzhou section of the Three Gorges Reservoir area were taken as the research objects. Through a physical model test with a large scale ratio, the variation of the water level at the monitoring points in the channel was determined, and the variation law of the water level in the whole channel was derived and converted into a prototype through the scale ratio. A model of the ship’s manoeuvring motion was established, and the ship’s manoeuvring motion characteristics in still water were verified. The correlations between the maximum roll angle and the navigation position, sailing speed, and rudder angle were investigated in detail. A safety risk response theory of navigation in the area of landslide-generated tsunamis was proposed, and a scientific basis was provided for the safe navigation of ships in the Three Gorges Reservoir area.

Description: Aiming at the bending performance of the prestressed superposing-poured concrete beam, the numerical simulation on the composite beams poured with the normal weight concrete (NWC) superposed on the fibred ceramsite lightweight aggregate concrete (LWAC) was conducted. Three kinds of prestressing schemes, straight linear prestressing force, curved prestressing force not across the casting interface, and curved prestressing force across the casting interface, were simulated for comparison, and the influence of the casting interval time was also considered. Results indicate that the stiffness of the superposing-poured beam can be effectively strengthened by considered schemes of the prestressing force; in addition, there are certain increases on the ultimate load except imposing the straight linear prestressing force. As the curved prestressing force is imposed across the casting interface, the maximal interlayer slip of the casting interfacial transition zone (C-ITZ) approximately equals to that without the prestressing force. The scalar stiffness degradation (SDEG) of the C-ITZ for the casting interval time being 14 days is obvious because of the weakening on the bonding performance of the C-ITZ. Comparatively, the SDEG variation of the C-ITZ in the model with the curved prestressing force across the casting interface is smoother and smaller on the whole than the other two prestressed schemes for the case of the casting interval time being 14 days.

Description: Forest biomass is an important ecological indicator for the sustainable management of forests. The aim of this study was to estimate forest aboveground biomass (AGB) by integrating SPOT-6 data with field-based measurements using the random forest (RF) algorithm. In total, 52 remote sensing variables, including spectral bands, vegetation indices, topography data, and textures, were extracted from SPOT-6 images to predict the forest AGB of Xuan Lien Nature Reserve, Vietnam. To determine the optimal predictor variables for AGB estimation, 10 different RF models were built. To evaluate these models, 10-fold cross-validation was applied. We found that a combination of spectral and vegetation indices and topography variables offer the highest prediction results (Radj2  = 0.74 and RMSE = 61.24 Mg ha−1). Adding texture features into the predictor variables did not improve the model performance. In addition, the SPOT-6 sensor has the potential to predict forest AGB using the RF algorithm.

Description: Base isolation can be used to reduce seismic response of structure and protect the structure from damage subjected to earthquake. To study the isolation effect of new PWR nuclear power plant with a base isolation system, considering FSI (fluid-structure interaction) effect by the simplified model, two 3D numerical models (one nonisolated model and one isolated model) were established. After natural frequency analysis, one artificial ground motion was chosen to analyze isolation effect qualitatively. Based on the results, the accelerations and relative displacements of nuclear island building under ten natural ground motions were statistically analyzed to evaluate the isolation effect quantitatively. The results show that the base isolation system can reduce the natural frequencies of nuclear island building. Horizontal accelerations can be reduced effectively, but the isolation effect is not obvious in vertical direction. The acceleration reduction ratio of the top is about 70%–90%, and the acceleration reduction ratio of the lower part is about 20%–60%. Horizontal displacement of the isolated model is far larger than that of the nonisolated model, and horizontal displacement will become larger considering FSI effect. These conclusions could provide some references for studies on the isolation system of nuclear island building.

Description: Agroecology was born as a competing theory to sciences derived from the Green Revolution like conventional agronomy or modernized animal husbandry. In recent years, several theoretical models or approaches have been developed in order to explain this science. However, any of them can explain its change or difference with its rival theories in a rational manner that allows assessment of its success. As a result, the aim of this study was to propose a rational model of scientific change based on main and auxiliary hypotheses. We found that seven basic principles have been formulated throughout theoretical books and papers as well as several auxiliary hypotheses that can be derived from them. These principles are as follows: (1) characteristic systemic principle of agroecology, (2) principle of biomimicry, (3) principle of biodiversity, (4) principle of specificity of agroecosystems, (5) principle of governance, (6) principle of socioecological resilience, and (7) principle of vulnerability. Also, three principles for food systems approach were retrieved. This model shows agroecology more like an organic theory that moves in different scales than a set of rival theories competing for success. However, a proper articulation and discussion of these basic principles is yet to be done.

Description: Background and Aims. An excessive and prolonged use of fertilizers undermines soils’ quality and, consequently, that of the crops they support, thus reducing the content of organic matter and generating environmental damages and problems to human health. Therefore, the use of biofertilizers such as cyanobacteria becomes a promising alternative. However, it is not always possible to generalize these fertilizers’ applicability, because microorganisms may be impacted by the physical and chemical variations of their environment. We will describe the action mechanisms or the characteristics of cyanobacteria involved in plant growth promotion for different crops in situ through a systematic review of scientific literature. Methods. A comprehensive search for original articles in two different databases, ScienceDirect and Scopus, was performed. We included in our search documents published from 2009 to 2018. After the screening process and the addition of gray literature publications, we obtained 23 articles for theoretical analysis. Results. The studies were distributed mainly in Asia and part of Africa, without any important temporal variation. They also showed a tendency to describe the use of cyanobacteria genera such as Anabaena sp., Nostoc sp., and Calothrix sp., besides mechanisms as N2 fixation, phosphate solubilization, phytohormone production, bioactive compounds excretion, and symbiotic associations, mainly on rice, wheat and corn crops. Conclusions. Cyanobacteria fertilizers used in situ are a widespread strategy, mainly in cereal crops. Their use is predominant in countries where cereal crops make an important contribution to their national economy. The great variety of mechanisms and characteristics of cyanobacteria used to promote plant growth in the field demonstrate the dramatic influence that physical, chemical, and biological variables have in their development.

Description: The joint force deformation of rock-concrete composite structures is different from that of simple rock specimens or concrete specimens, such as the tunnel surrounding rock-lining concrete, dam foundations, and concrete. In order to study the creep mechanical properties of rock-concrete composite structures under long-duration load, the TFD-2000 microcomputer servo triaxial creep testing machine is used to carry out step loading creep tests on rock-concrete composite specimens (hereinafter referred to as composite specimens) under different confining pressures (including the confining pressures σ3 = 0 MPa). The creep test results show that, under the same confining pressure, when axial deviatoric stress is applied step-by-step according to 10%, 20%, 30%, 40%, 50%, and so forth of the UCS (σ3 = 0 MPa) and TCS (triaxial compressive strength) of the composite specimens, the failure stress that the specimen can bear is closely related to the confining pressure. When the confining pressures are 0 MPa, 7 MPa, 15 MPa, and 22 MPa, respectively, the failure stresses that the composite specimens can bear are 60% (corresponds to 0 MPa), 50%, 30%, and 20% of the TCS under the current confining pressures, respectively. Under the same confining pressure, the initial creep rate of the composite specimen on each step shows a U-shaped change trend. Meanwhile, the instantaneous creep rate and failure creep rate of the specimen increase as the confining pressure increases. When the failure creep rate is excluded, the initial creep rate of other stepped loads at the same confining pressure level decreases step-by-step. The improved Nishihara model can better describe the whole creep process of rock-concrete composite specimens, especially in the accelerating creep step. The testing data and research results in this paper can serve as references for further research on mechanical properties of rock-concrete composite structures.

Description: Flowslides, as one type of landslides, are becoming a research hotspot due to their high speed and long runout distance, which can cause tremendous damage and economic loss. The scale of damage and deposit morphology of flowslide is closely related to factors like deposit volume, slope height, and slope angle. In order to assess the influence of these factors, a sandbox apparatus is developed, and the Taguchi method is used to design an experimental scheme to analyze the results of factors affecting the deposit morphology of flowslide. The results show that the factor that has the greatest impact on flowslide deposit morphology is slope angle, followed by the influence of volume and slope height. As slope angle increases, the maximum width, maximum length, area, and length-width ratio of the deposit first increase and then decrease. In addition, there should be a critical angle in the changes of deposit morphology that is between 60° and 70° under the experimental conditions. When the volume is 5.4 × 10−3 m3, the slope angle is 70°, the slope height is 0.90 m, and the changes of deposit morphology of the flowslide are the largest. In this study, considering the slope angle as a single variable, there is a single upheaval for a slope angle of 40° and 50° and a double upheaval at 60° and 70°. The formation mechanism of the upheaval is analyzed based on the Mohr-Coulomb criterion and considered properties of the material. The apparent friction coefficient of a flowslide is spatially and lithologically different and increases nonlinearly as the slope angle increases. The initial benchmark of the slope angle and apparent friction coefficient curve are affected by the friction coefficient of the material; the position of the inflection point at which the curve increases rapidly is affected by the coefficient of velocity restitution.

Description: The addition of chemical or mechanical materials, such as fibers or stabilizers, is frequently utilized in geotechnical engineering to improve the mechanical properties of problematic soils. In this study, great efforts have been made to obtain insight into the mechanical properties of the natural, fiber, and chemical additive-stabilized soil in heavy-haul railway embankment. A series of triaxial compression tests are conducted on the stabilized samples of different preparation conditions, including water content, compaction degree, confining pressure, fiber content, fiber length, stabilizer content, and curing time. Results show that the shear strength of natural soils shows a distinct increase after adding fiber and chemical additive stabilization. The optimum fiber content and length for fiber stabilization are 0.2% and 12 mm, respectively. The initial tangential modulus and failure stress of chemical stabilized samples increase with the increase of additive dosage or curing time. Meanwhile, a brittle characteristic is observed. In the process of determining the reinforcement methods in practical projects, several other considerations are included, such as equipment and time available, especially for stabilized soils. The fiber-reinforced soils and stabilized soils are efficient for increasing the shear strength and changing of the brittleness character of the heavy-haul railway embankment. The results of this study could provide a valuable reference for geotechnical engineers dealing with soil problems, especially for the heavy-haul railway embankment.

Description: Empirical evidence shows complementarity between maize and soybean as a sustained agricultural system across North and South America as well as Eastern Europe. The potential application to sub-Saharan Africa motivates this literature review. Maize is one of the most important crops on the African subcontinent, accounting for over half of daily caloric intake in some regions. However, continuous cropping of maize has led to extensive degradation of soil and decrease in crop productivity and endangers household food and nutritional security. The cultivation of soybean holds great promise in improving agricultural systems in sub-Saharan Africa. Introducing soy into rotation with maize is a method to diversify diets, better nutritional status, reduce abiotic and biotic stresses, and improve soil fertility, while enhancing crop productivity and generating more income for farmers. However, limited access to extension services and other sources of technical support constrains adoption of the more complex rotation cropping system involving a new crop, soybean. Rotating soybean with maize too challenges farmers as there is not a specific prescription that can guide farmers operating across Africa’s diverse agroecological environments. Finally, soybean is an input-intensive crop requiring significant investment at planting, which may not allow small holders with limited resources and no access to credit.

Description: Taylor’s φ-circle method is a classical method for slope stability calculation, which has analytical solutions. Taylor derived equations in two cases separately, namely, (i) the outlet of the critical failure surface is at the slope toe and (ii) the outlet of the failure surfaces is not at the slope toe. The method is only appropriate for two conditions (without underground water table in slopes or totally submerged slopes). In this study, a general equation that unifies the equations of the two cases is proposed and partially submerged condition is introduced. The critical failure surfaces corresponding to the minimum factor of safety are determined using the computer program proposed by the authors. The general expression of the safety factor of slopes under the following four conditions is derived, namely, (i) partly submerged, (ii) completely submerged, (iii) water sudden drawdown, and (iv) water slow drawdown. The corresponding charts for practical use are available.

Description: A small-scale double-hole bench model is designed with granite to study the fracture mechanism of rock blasting. By combining high-speed camera and digital image correlation, the full-field strain characterization and fracture process of the specimen bevel surface are investigated. The preliminary test results show that the strain concentration zone corresponds to the crack propagation location, and digital image correlation can well detect the crack propagation. In addition, through observing the crack propagation pattern on the specimen bevel surface, it can be seen that the fracture of the specimen is caused by the dominant horizontal crack and the dominant vertical crack, and the generation of the dominant horizontal crack takes precedence over that of the dominant vertical. Finally, the measurements of two-dimensional digital image correlation and three-dimensional digital image correlation are discussed.

Description: The comprehensive understanding of the variation law of soil thermal conductivity is the prerequisite of design and construction of engineering applications in permafrost regions. Compared with the unfrozen soil, the specimen preparation and experimental procedures of frozen soil thermal conductivity testing are more complex and challengeable. In this work, considering for essentially multiphase and porous structural characteristic information reflection of unfrozen soil thermal conductivity, prediction models of frozen soil thermal conductivity using nonlinear regression and Support Vector Regression (SVR) methods have been developed. Thermal conductivity of multiple types of soil samples which are sampled from the Qinghai-Tibet Engineering Corridor (QTEC) are tested by the transient plane source (TPS) method. Correlations of thermal conductivity between unfrozen and frozen soil has been analyzed and recognized. Based on the measurement data of unfrozen soil thermal conductivity, the prediction models of frozen soil thermal conductivity for 7 typical soils in the QTEC are proposed. To further facilitate engineering applications, the prediction models of two soil categories (coarse and fine-grained soil) have also been proposed. The results demonstrate that, compared with nonideal prediction accuracy of using water content and dry density as the fitting parameter, the ternary fitting model has a higher thermal conductivity prediction accuracy for 7 types of frozen soils (more than 98% of the soil specimens’ relative error are within 20%). The SVR model can further improve the frozen soil thermal conductivity prediction accuracy and more than 98% of the soil specimens’ relative error are within 15%. For coarse and fine-grained soil categories, the above two models still have reliable prediction accuracy and determine coefficient (R2) ranges from 0.8 to 0.91, which validates the applicability for small sample soils. This study provides feasible prediction models for frozen soil thermal conductivity and guidelines of the thermal design and freeze-thaw damage prevention for engineering structures in cold regions.

Description: The upper reaches of Min River (The upper Min River) is located in Southwest China with significant mountain settlements, which are vulnerable to frequent geological hazards. Based on a field investigation, collation of yearbook data, and analysis through the use of SPSS statistical software, a vulnerability evaluation index system of geological hazards was devised. According to the actual field situation and the acquired data of the study area in 2006, 2009, and 2015, 16 indicators were selected as settlement vulnerability evaluation indexes of geological hazards. The indexes included population density, building coverage, and economic density. Based on the comprehensive evaluation model of entropy value, the dynamic change in the settlement vulnerability of geological hazards was analyzed. The results showed that population density, building coverage, economic density, and road density were the factors that affected the settlement vulnerability of geological hazards the most—Wenchuan earthquake caused considerable damage to the upper Min River, making the area the most vulnerable in 2009. However, its vulnerability decreased in 2015, which indicated that postearthquake reconstruction achieved significant results. Thus, the vulnerability has emerged as an important indicator reflecting the safety and healthy development of mountain settlements.

Description: The seismic dynamic response and correlation between various indicators of an arch dam under a series of stochastic earthquake excitation are analysed. Seismic response assessment of a concrete arch dam is conducted through nonlinear endurance time analysis (ETA) of a typical arch dam. The 289 m high Baihetan arch dam in Southwest China (as a case study) is subjected to a set of 10 three-component endurance time acceleration histories (ETAHs) synthesised on the basis of the design site acceleration response spectrum to increasing peak ground acceleration (PGA). The effects of dam-reservoir-foundation interaction, radiation damping of infinite rock foundation, and nonlinearities of dam material and joint contact elements are considered. The indices to failure modes of damage propagation through the dam body and the deformation and joint opening beyond the limit states of the arch dam are identified. Dynamic responses, including deformation, joint opening, and damage distribution, are statistically analysed. The dispersion and correlation of indicators are analysed by employing the coefficient of variation and coefficient of correlation, respectively. The deterministic relationships between contraction joint opening, displacement, and damage volume ratio are obtained by using a multivariate fitting method. The results show that those failure indices have similar exponential trends, and seismic intensity parameters exert a significant influence on seismic response and damage under increasing PGA. The results of correlation and fragility analysis demonstrate that damage volume ratio and the sum of joint opening are consistent, which can provide a strong scientific basis for predicting earthquake damage.

Description: Longwall mechanized top coal caving mining (LMTCCM) in extra-thick coal seams has its own characteristics. The law of mining pressure and overlying strata failure height in extra-thick coal seams are much larger than those of medium-thick and thick coal seams. The key stratum structure morphology also has an important influence on the law of overlying strata movement and stability of surrounding rock. Based on the engineering geological conditions, this paper used the method of theoretical analysis and numerical simulation to study the key stratum structure morphology of LMTCCM in extra-thick coal seams. The results show that under the condition of LMTCCM in extra-thick coal seams, the key stratum forms the structure of low cantilever beam and high hinged rock beam. With the increase of coal seam thickness, the breaking position of cantilever beam is closer to the coal wall. Through theoretical calculation, it is obtained that the breaking length of cantilever beam is 31.5 m and the breaking position of cantilever beam is 15.4 m away from coal wall. With the increase of cycle, key strata will undergo the evolution law from the generation of longitudinal cracks to the hinged structure and then to the cantilever beam structure. The breakage of key strata will cause the expansion of longitudinal cracks and the overall synchronous movement of overlying strata. With the increase of coal seam thickness, the distribution of longitudinal cracks will gradually transfer from the upper part of goaf to the deep part of coal body in space and increase in quantity. This research is of great significance for improving the stability of overlying strata and ensuring the safe and efficient mining of extra-thick coal seams.

Description: A series of settlement, cracking, and collapse of the Zhengjiaping slope has been increasingly developing since October 2015 during impoundment at the Dagangshan Hydropower Station. It is a dangerous signal, which means thatlandslide potential will be existed for the Zhengjiaping slope and poses greatthreat to the operation of hydropower station and traffic safety. Related slope protection measures and research studies have been implemented accordingly in the Zhengjiaping slope to prevent and control adverse influences on property security and human life in the reservoir area. In order to understand the geological and hydrological settings of the Zhengjiaping slope and its surroundings, a field investigation was carried out to determine the lithological composition and toppling/sliding deformation characteristics using exploratory adit and site boreholes. The large deformation process in the apparently deformed area was analyzed using borehole inclinometers and global navigation satellite systems (GNSS). It was found that the apparently deformed area zone was characterized by crushed rock masses, with only a small amount of slope deposits and the sliding deformation occurring in Zone I. The deformation process of the reservoir landslide was considered to be a complex integration of the geological effects of various adverse factors. Impoundment and heavy rainfall are the direct causes of sliding deformation. During the preparation of the basic conditions for sliding, lithology, tectonic activity, and artificial disturbances play an important role, including the sliding mass and the sliding surface zone.

Description: In the drilling and blasting excavation of underground rock mass, the stress wave produced by the blasting holes usually propagates in the form of cylindrical wave, while the rock mass surrounding the underground engineering is initially subjected to the in situ stress. To explore the propagation and attenuation law of cylindrical stress wave in the in situ stressed rock mass, a model test of cylindrical blasting stress wave propagation across the intact and jointed rock mass under different initial stresses was carried out. First, the attenuation law of the cylindrical stress wave in the intact rock mass under different confining pressures is analysed, and then the influence of the confining pressure scales, the angle, and the number of joints on the propagation law of the cylindrical blast wave in the jointed rock mass is studied. The experimental results show that the physical attenuation of the cylindrical wave in the intact rock mass decreases and then increases as the confining pressure increases from zero. Under zero confining pressure, the transmission coefficient of the cylindrical wave in the jointed rock mass decreases with the increase of joint angle, and the transmission coefficient increases with the increase of the joint angle under confining pressure. As the confining pressure increases from zero, the transmission coefficient shows a trend of increasing firstly and then decreasing.

Description: The extract of Nicotiana tabacum L. var Virginia origin of Ponorogo (EHRE-Nt) was applied under field conditions against the coffee borer beetle Hypothenemus hampei (CBB). Three extract formulations containing 150, 300, and 450 ml of EHRE-Nt in 100 liters of water were prepared and sprayed on 0.5 hectares each. A nontreatment was applied as a control on 0.5 hectares of plantation. The intensity of the CBB attacks was observed for six weeks on a Robusta coffee plantation in the Kalibening area, South Semarang, Central Java, Indonesia. An extract formulation containing 450 ml of EHRE-Nt resulted in the lowest intensity of CBB attacks from weeks one to six (1.6% to 2.2%). The attacks of the control field were 11.3% to 13.5%. The highest efficacy level of 85.4% was obtained with the 450 ml EHRE-Nt formulation. These results demonstrate that EHRE-Nt has potential as a bioinsecticide for coffee berries from CBB attacks.

Description: This study aims to evaluate the sensing performance of glass fiber-reinforced polymer (GFRP) rock bolt sensors instrumented with strain gauges for monitoring rockslides. Experimental studies are conducted with four different types of GFRP rock bolt sensors and concrete blocks having central holes and two shear joints. Two GFRP rock bolt sensors are inserted into holes and then fixed in concrete blocks with cement grout and soil, respectively. The other two are coated with heat-shrink tubes to protect strain gauges and wires, which are then fixed in concrete blocks with cement grout and soil, respectively. Double shear tests are performed to produce shear deformations of GFRP rock bolt sensors, and then strain change with shear displacement is monitored. The results manifest that the variation in strain with shear displacement is more sensitive in the GFRP rock bolt sensor fixed with soil than with cement grout. Also, strain gauge wires in the GFRP rock bolt sensor fixed with cement grout are broken earlier than with soil. Furthermore, it is confirmed that the heat-shrink tube effectively protects strain gauges and wires, so that GFRP rock bolt sensors coated with heat-shrink tubes work for a longer time than the uncoated sensors. The present study shows that the GFRP rock bolt sensor can be useful for monitoring rock slope failure.

Description: Out-fashioned goaf is the protective structure for mining the upper residual coal, and its stability is the core problem in mining the upper residual coal. According to the upward mining demand for No. 5 coal seam above the out-fashioned goaf in Baizi Coal Mine, a new method is proposed to determine the upward mining safety. According to the analysis of the actual situation of the mine, the coal pillar and suspended roof in the out-fashioned goaf are taken as the objects. Furthermore, a “coal pillar-suspended roof” system model based on the variable load induced by abutment pressure of upper coal seam mining is established. After the mechanical model was solved, the parameter acquisition method of the model was established. The basic parameters of Baizi Coal Mine were considered to determine the feasibility of mining residual coal above out-fashioned goaf. And the effects of variable load on the coal pillar and suspended roof stability were analyzed. The results show that the upper No. 5 coal seam in Baizi Coal Mine can be mined safely. Compared to the traditional method, which simplifies all the upper loads to uniform loads, the new method is safer. The system stability of the suspended roof and coal pillar is influenced by “a/L” and “L.” Axial stress curves of the coal pillar and suspended roof appear nearly parabolic with “a/L” varying. Their maximum values are obtained when the “a/L” value is around 0.5∼0.6. In this situation, the combination structure is most easy to to be damaged. The ratio q′/q has a linear relationship with all stresses of the system model. The failure sequence of the system model is determined by analyzing the relationship between the tensile strength of the suspended roof and compressive strength of the coal pillar. This study provides a reference case for coal resources upward mining under similar conditions.

Description: An experiment was conducted to examine the performance of pearl millet under different nitrogen (N) fertilizer rates in two locations in the semiarid zone of Nigeria. The objective was to evaluate the effects of different N rates on pearl millet yields, water- and nitrogen-use efficiency, and profitability. Grain yield increased by 23, 26, 32, 32, and 27% and by 38, 41, 54, 58, and 56% compared to unfertilized plots when applying 20, 40, 60, 80, and 100 kg Nha−1 in Minjibir and Gambawa, respectively. Similarly, stalk yield increased by 4, 3, 9, 9, and 9% and by 16, 24, 36, 40, and 37% compared to unfertilized plot when applying 20, 40, 60, 80, and 100 kg Nha−1 in Minjibir and Gambawa, respectively. The variations in GY that could be explained by TWU and NUE were 28% and 26% in Minjibir and 46% and 41%, respectively, in Gambawa. There was a strong and positive correlation (R = 0.81 and R = 0.95) between WUE and GY across N-fertilizer rates and pearl millet varieties in both locations. An increase in N-fertilizer levels increased WUE, confirming the optimal application of 60 kg Nha−1 in Minjibir and of 80 kg Nha−1 in Gambawa. Similarly, the highest net economic return (NER) of US$610 ha−1 was obtained at 60 kg Nha−1 in Minjibir and the highest NER of US$223 ha−1 was obtained at an application rate of 80 kg Nha−1 in Gambawa. Break-even yield was above 1000 kg ha−1, signifying that average farmer with a mean yield of less than 1000 kg ha−1 produces millet at a loss.

Description: The traditional Coulomb’s earth pressure theory does not consider the effect of local surcharge on the lateral earth pressure and its critical failure angle. However, in practice, local surcharges commonly act on the surface of frozen backfill that is affected by freeze-thaw actions in cold regions and tend to affect the active thrust and its position. In paper, analytical solutions for estimating the active thrust, critical wedge failure angle, and action position subject to a local surcharge in cold regions are proposed. Herein, the simplified equivalent moment of surcharge is adopted on the premise of maintaining Coulomb’s earth pressure assumptions. The formula derivation is provided as a typical example to obtain the active thrust, critical wedge failure angle, and its position under a strip surcharge. Compared with previous approaches, the proposed solutions lead to easier evaluation of all indexes associated with Coulomb’s active earth pressure. Meanwhile, the expressions of Coulomb’s earth pressure under other types of nonuniform loading acting on the wall are discussed. In addition, sensitivity is performed to assess the effect of some main parameters. The results indicate that the dip angle of retaining wall-back and the friction angle of frozen backfill soil are two most significant indexes that influence the active thrust and its position.

Description: This paper presents an experimental investigation on the dynamic characteristics of soft soils that are treated by vibration-drainage method (VDM). The representative dynamic axial strain at a given number of cycles was obtained. The VDM-treated soft soil exhibited different dynamic deformation characteristics that are not only affected by the cyclic frequency but also influenced by the vibration frequency during the treatment process. Soil specimens at different cyclic frequencies show a similar variation trend that the axial strain systematically grows with increasing number of cycles. The rate of axial strain for all specimens systematically linearly decreases with the increase of number of cycles in the log-log scale. Results showed that both axial strain and strain rate exhibit relatively lower values at a given number of cycles under the condition that the applied cyclic frequency is equal to vibration frequency. It is expected that the soil structure will be more stable if the applied cyclic frequency is close to the vibration frequency that is applied on VDM-treated soil. Therefore, the vibration frequency close to the possible dynamic loading frequency is recommended in the process of soft soil improvement via VDM in the related engineering applications.

Description: To improve the antifreeze-thaw performance of asphalt pavement in the seasonal freezing regions, the temperature and the time of freeze-thaw test were redesigned based on the climatic characteristics of the regions, and the splitting tensile strength tests were carried out to determine the low-temperature performance of the asphalt mixture under the influence of the gradation and the asphalt-aggregate ratio. A mathematical model was built to investigate the freeze-thaw damage law. According to the test results of splitting tensile strength of the asphalt mixture under freeze-thaw cycles, the probabilistic damage variable of the asphalt mixture was redefined and a physical probability model was built to analyse the freeze-thaw damage. Based on the freeze-thaw damage development process and the mechanism of the asphalt mixture, the effective measures to improve the antifreeze-thaw performance were provided and demonstrated through the correlations among the damage parameters (the shape parameter α, the scale factor λ, and the gradient factor ν) and the freeze-thaw resistance of the asphalt mixture. The test results showed that the splitting tensile strength decreased with the increase of the number of the freeze-thaw cycles. With the same gradation, the splitting freeze-thaw damage degree of the asphalt mixture with 5.8% asphalt-aggregate ratio is about 6% less than others after the 18th freeze-thaw cycle. The freeze-thaw resistance increases with the asphalt-aggregate ratio. With the same asphalt-aggregate ratio, the splitting freeze-thaw damage degree of S-grade mixtures is about 11.8% higher than that of Z-grade mixtures. S-grade mixtures have positive effects on the freeze-thaw resistance. The results suggest new measures for further investigation on the design and maintenance of the asphalt mixture in the seasonal freezing regions.

Description: Carbonaceous rock is a special soft rock containing TOC organic carbon 6%∼40%. In order to reveal the influence of engineering characteristics of carbonaceous rock on the engineering construction, firstly the stratigraphic distribution of carbonaceous Rocks in Guangxi is investigated, and the genetic mechanism and tectonic environment of carbonaceous rocks are discussed. Secondly, the influence of pore microstructure on the disintegration characteristics of carbonaceous rocks is analyzed. The role of geochemical characteristics of carbonaceous rocks (mineral composition, TOC total organic matter content, and type) on engineering properties is revealed. Finally, combined with the distribution, structure, microstructure, and microscopic characteristics of the previous studies, the disintegration mechanism of carbonaceous rocks in water swelling and heat dehydration is discussed. The results are as follows. (1) Carbonaceous rocks in Guangxi are mainly distributed in Devonian, Carboniferous, and Cambrian systems. It is mainly formed in anoxic and reductive deep water basins, slopes, and relatively confined coastal lagoons and swamps. The carbonaceous rocks in the Devonian Luofu formation are most typical. (2) The pores of carbonaceous rocks are divided into mineral pores, organic matter pores, and microfracture, which are mainly mineral pores. The more developed pores in mineral pores are intragranular dissolved pores. Secondly, mineral intergranular pores and a small amount of intergranular dissolution pores and less inner pores. Organic matter porosity increases with the increase of shale organic carbon content and maturity, but the shale porosity and adsorption capacity decrease when shale maturity reaches more than 2.4%. (3) Clay minerals in carbonaceous shale mainly consist of illite and illite/montmorillonite layer, which have water swelling and heat dehydration. The total average value of TOC (total organic matter content) is more than 1%, which belongs to carbonaceous rocks of medium high grade hydrocarbon source rocks. Organic matter is mainly dominated by type I and II1-II2 type with large hydrocarbon generating potential, which is prone to oxidation-reduction reaction and cause rock disintegration.

Description: The two-component foaming polyurethane is a kind of grouting material that has recently been widely used in engineering structural repair. Its physical and mechanical properties are closely related to its microstructure. Therefore, the qualitative and quantitative analysis of polymer microstructure has always been a research hotspot. The statistical characteristics of polymer grouting material microstructure are investigated by six groups of specimens with different densities, and the density varies from 0.1 to 0.6 g/cm3. The microstructure morphology of polymer was observed and described by scanning electron microscopy (SEM), and the microstructure feature parameters were extracted and calculated by image processing technology. The quantitative analysis of section cell roundness distribution, cell diameter distribution, and polymer porosity shows that low-density polymer materials have anisotropy. While the density exceeds 0.3 g/cm3, the cell structure tends to be spherical. The section cell diameters obey a normal distribution, and when the density increases, the cell diameter decreases. The porosity of the polymer has a linear negative correlation with the density. The polymer matrix has a density of 1.21 g/cm3. The microstructural information obtained in this study will help establish a cell-based model to explain the mechanical response of rigid polymer foams.

Description: Ultra-high-performance concrete (UHPC) is already gaining in-field applications in bridge deck rehabilitation. On the other aspect, an innovative NC-UHPC composite deck system was motivated to promote accelerated bridge construction (ABC) implementation of a newly built bridge, of which the precast UHPC substrate serves as the formwork for the cast-in-place NC overlay. Performance characterizations were investigated by loading five decks, of various UHPC thickness and w/wo longitudinal or transverse rebars. Their effects on the composite decks’ failure patterns and load-deflection curves were quantitatively analyzed. Besides, digital image correlation (DIC) technique was adopted to adequately capture their damage evolutions. Moreover, analytical solutions for predicting a composite deck’s flexural and shear strengths are tentatively derived. Finally, 3D finite element (FE) models are developed within ATENA framework, capable of embracing the NC-UHPC interface’s behaviors. Numerical predictions agree well with the experimental results and can benefit further researches evolving a NC-UHPC composite deck system.

Description: Cemented paste backfill (CPB), a mixture of tailings, binder, and water, is widely and continually utilized in underground mines for subsidence control and disposal of surface hazardous waste discharge. The mechanical strength of CPB, which is the key for the backfill structure to play the role of supporting overlying roof and controlling subsidence, is governed by complex factors (thermal, hydraulic, and mechanical loads), particularly strongly affected by the environmental conditions, such as ambient temperature and humidity. Thus, it is crucial to understand and assess the response of CPB subjected to the loads mentioned above, so as to better ascertain its performance and obtain a cost-effective, safe, and stable CPB structure. Accordingly, a coupled THM model is developed to describe and analyze the performance of CPB. Comparisons between model simulation and experiment data prove the capability of the developed model in predicting the evolutions of temperature and internal relative humidity, as well as stress-strain relation of CPB. The obtained results indicate that all these properties are significantly affected by ambient humidity and temperature.

Description: To study the effect of short-cut basalt fiber (BF) on the bending and toughening properties of shotcrete, bending toughness tests of short-cut BF shotcrete slabs with different volume fractions were carried out. A transparent soil model and Scanning Electron Microscopy (SEM) were used to observe the distribution of BF with different volume fractions and analyze the toughness enhancement mechanism of basalt fiber shotcrete. The supporting effect of basalt fiber shotcrete with different volume fractions was verified by an underground engineering test. The test results show the following: (1) when the fiber content is within 3∼4.5 kg/m3, the distribution of BF in transparent soil is uniform, and it does not easily agglomerate, which is beneficial to improving the bending toughness of shotcrete. (2) The shotcrete slab with 4.5 kg/m3 fiber content had the best reinforcing effect. Compared with the control group, the peak load and absorption capacity increased by 56.67% and 636.96%, respectively, and the maximum crack width decreased by 32.10%. (3) The SEM analysis indicated that the basalt fibers distributed randomly and evenly in the concrete, which can form a three-dimensional spatial skeleton with a stable structure. Excessive fiber incorporation can increase fiber agglomeration during stirring and spraying. (4) The support results of an underground engineering test show that, in 35 days, short-cut basalt fiber shotcrete with 4.5 kg/m3 fiber content is better at restraining the surrounding rock than shotcrete with other fiber contents. BF has the properties of crack resistance, bridging, and toughening for shotcrete and can significantly improve the ability of shotcrete to restrain surrounding rock deformation. As a new type of fiber, BF has great significance in deep soft rock underground engineering.

Description: Determination of the required supporting pressure is the premise of tunnel support design. Only when the support design meets the requirements can the tunnel be safe and stable during construction and operation. This paper focuses on a shallow tunnel in layered rock strata and proposes a method for predicting the required supporting pressure. In this method, the 2D and 3D failure mechanisms are constructed, respectively. The analytical solutions of the supporting pressure corresponding to the two cases are derived on the basis of upper bound theorem and Hoek–Brown failure criterion. Then, the proposed method is validated by comparing with the results of existing research studies. Furthermore, a shallow tunnel in two-layer rock strata is chosen to illustrate the difference between the two solutions. The comparison shows that the supporting pressure in the 2D case is greater than that in the 3D case in general and it tends to be conservative for tunnel design. Conversely, the 3D solution may help to reduce the support cost. Furthermore, the change laws of the supporting pressure and failure range corresponding to varying parameters are obtained. These results may practically provide theoretical references for tunnel support design in layered rock strata.

Description: Linz-Donawitz (LD) slag, solid waste produced during steel manufacture in basic oxygen furnace, is difficult when it comes to handling and disposal and has very limited utilization. To increase its reusability, the suitability of supplanting cement with LD slag in concrete was examined. To study the impact of partially replacing cement with LD slag on strength, microstructure, and durability of concrete, more than 150 samples were cast. The test results reveal that the highest compressive and flexural strengths were attained at 20% LD slag replacement and, beyond that, the strength decreased. The hydration products detected by X-ray Diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) were calcium silicate hydrate (C-S-H), ettringite, and calcium aluminosilicate hydrate (C-A-S-H). The scanning electron microscope (SEM) images of binary cement concrete showed denser microstructure and lesser voids. The sulphuric acid resistance, electrical resistivity, and carbonation resistance tests done reveal that acceptable durability could be achieved when cement is replaced by LD slag. It is deduced that LD slag can be utilized in partially replacing cement to achieve the desired strength. This research gives another comprehension of simultaneously managing steel industry waste for sustainable development and contributing added advantages to the economy.

Description: Forestry related projects fail due to the lack of participation by the community during the initiation stage. This further leads to unsustainable management of forests. This study was undertaken to examine how participatory project initiation influences sustainable forest management in Saboti forest in Trans-Nzoia County, Kenya. Participatory Development Theory guided this study. The explanatory research design was adopted. The target population was 2600 community forest association (CFA) members and 15 Kenya Forest Officers. Census sampling was used in the sampling of Kenya forest Officers and simple random sampling to select community forest management members. The sample size was 347 community forest management members and 15 Kenya forest Officers. Data were collected using questionnaires and through interview. Data were analyzed using descriptive and inferential statistics. Presentation of findings was carried out using tables. There was a significant influence of participatory project initiation on sustainable forest management (SFM) (r = 0.700, p=0.00). This implies that an increase in participatory project initiation improved sustainable forest management in Saboti. Participatory project initiation had a significant influence on sustainable forest management. The community participation in initiation had a significant influence on sustainable forest management. There is need for forest management to involve the community members during the initiation stage of the projects in order to achieve sustainable forest management.

Description: The experimental work presents results on the fatigue performance of composite beams in the negative moment region and the changes of stiffness and deformation of composite beams under repeated loads; fatigue tests were carried out on two double-layer composite beams. The fatigue performance of composite beams with different reinforcement ratios under complete shear connection and the variation of deflection, strain of the reinforcement, strain of steel beam, and crack growth under fatigue load were obtained. The results showed that the fatigue resistance performance of concrete slab with low reinforcement ratio was much lower than that of concrete slab with high reinforcement ratio whereas, under the fatigue load, the stress of the welding nail in the negative moment region was small and the slip was almost negligible. The degradation of stiffness and the development of cracks were mainly due to the degradation of bond-slip between the concrete and reinforcement. The fatigue failure mode was the fracture of the upper reinforcement in negative moment region. The results obtained in this study are helpful in the design of composite beam.

Description: Antislide piles are set in the Zhangjiawan landslide area, where the general features of the bedrock below the slip surface include upper weak and lower hard strata. Based on a site investigation, the horizontal displacement of the antislide pile head is 14.8 cm, which is not conducive to the stability of the landslide. In the study, a displacement calculation method for the pile under trapezoidal load is proposed for a colluvial landslide controlling. Furthermore, factors affecting the deformation and internal forces of the pile were also studied. The results indicated that (1) when the embedded length of an antislide pile increases, the horizontal displacement on the pile and maximum absolute shear force decrease, while the bending moment of the pile exhibits opposite trends; (2) the relationship between maximum shear force and maximum bending moment is linear with increasing driving force of landslide; and (3) increase in the ratio of the driving force between the pile head and slip surface (q0/q1) steadily increases the horizontal displacement of the pile. The relationship between the distribution of the driving force (q0/q1) and the reasonable embedded length of a pile is a quadratic function, which can be used to determine the reasonable embedded length of a pile under the action of rectangular or triangular loads. It is very useful to use the above method to guide the design of antislide piles in similar areas.

Description: The literature related to earthquakes and fibre reinforced polymer (FRP) retrofitting can be divided into two main categories: (1) the applications of FRP to retrofit structures subjected to single traditional earthquakes and (2) the effects of mainshock-aftershock sequences on original structures (without FRP retrofitting). Research on using FRP to mitigate the risk of pulse-type mainshock-aftershock sequences for reinforced concrete (RC) structures located in near-fault regions is hardly found in the literature and is thus the aim of this study. To achieve this aim, a four-storey RC frame, near-fault mainshocks, and seismic sequences were selected. The frame was retrofitted using FRP wraps at plastic hinge locations. Nonlinear time history and damage analyses of the original and FRP-retrofitted frames subjected to these near-fault mainshocks and seismic sequences were conducted. The results showed that aftershocks significantly increase the damage indices of the frames, shifting the damage state of the original frame from severe damage to collapse and the damage state of the FRP-retrofitted frame from light damage to moderate damage. FRP retrofitting successfully reduced the risk of seismic sequences by reducing the damage two levels, shifting the damage state of the original frame from collapse to moderate damage.

Description: The aim of this work is to explore the influence of the end resistance and shaft resistance regarding the mechanism for jacked pile penetration and the load-transfer rule during the penetration process. A full-scale field test was conducted in an actual project located in Dongying, Shandong Province, China. In this test, the axial strain experienced by two closed Prestressed High-strength Concrete (PHC) pipe piles during jacking into layered soil was monitored successfully using Fiber Bragg Grating (FBG) sensors mounted on the pile shaft. The experimental results show that FBG sensors have a good stability, strong antijamming performance, and can effectively monitor the pile stress. The variation law of the jacking force reflects the distribution of the soil layer, and the hardness of the soil layer at the pile end limits the pile force. When the pile end enters the silt layer from the clay layer, the jacking force and shaft resistance increase by 2.5 and 1.7, respectively. The shaft resistance accounted for 44.99% of the jacking force. The end resistance is affected by the mechanical properties of soil, and the end resistance of the silt layer is approximately twice that of the clay layer. The end resistance of the silt layer accounted for 59.84% of the jacking force. When the pile end enters the soft soil layer from the hard soil layer, the impact of the pile driving speed and the tangential force on the surface of the pile body must both be considered. During the pile penetration process, as the penetration depth increases, the radial stress on the pile side at a given depth is gradually released, while the shaft resistance at the pile side degrades significantly.

Description: Tomato production is constrained by fungal diseases especially the early and late blight caused by Alternaria solani and Phytophthora infestans, respectively. Control of the two diseases is usually by use of synthetic fungicides which have a long residue effect and also contribute to environmental pollution. Innovative use of biocontrols may offer an eco-friendly and more sustainable solution. This study tested the in vitro efficacy of crude extracts and essential oils of ginger, garlic, tick berry, and Mexican marigold in inhibition of radial growth of A. solani and P. infestans. Extraction of the crude extracts was done using distilled water, ethanol, and methanol solvents, while essential oils were extracted using the dry steam distillation method. The extracts and essential oils were used to amend the growth media of the test pathogens before introducing the precultured pathogens. Sterile distilled water and synthetic fungicide, Ridomil Gold®, were used as positive and negative controls, respectively. Fungal growth inhibition was determined by measuring the radial growth of the test pathogens. Both the crude extracts and the essential oils portrayed some efficacy against the test pathogens. Garlic crude extracts were found to be the most effective, while ethanol was the most suitable extraction solvent. Essential oils were more effective in restricting the pathogen growth than crude extracts. Ginger and garlic oil was found to be as effective as the synthetic fungicide, and thus it was concluded that the two plants have strong antifungal properties with high potential of being utilized as biofungicides. However, effective utilization of these products in farmers’ fields may require industrial formulation to improve their efficiency.

Description: In view of difficult problems such as excavation, segment simulation, deformation, and force measurement in the small-scale model testing of deep composite stratum TBM tunnel, the TBM simulation experimental device, the model segment ring prefabrication device, and the digital photogrammetry technology were comprehensively adopted. Also, the calculation methods were proposed. The analysis of the deformation characteristics as well as rupture of surrounding rock revealed those space-time effects: (1) When no support existed, the space-time effect of the surrounding rock deformation was concentrated in the following case: with the development of time, the deformation of surrounding rock starts from the sides of the arch waist at the junction of the composite stratum, while four arcs were derived and shear sliding occurred, resulting in overall collapse and destruction. (2) Following the support application, the space-time effect of the surrounding rock deformation was concentrated on the three stages of the interaction between the surrounding rock and the support, namely, the preliminary stage, the equilibrium process, and the instability state. The spatial effect was concentrated in the area where the surrounding rock was deformed and destroyed. The most severe area was the shallow surrounding rock, while the sub-violent area was the corner of the sidewall.

Description: Shake table tests were performed on three two-story 1 : 3 reduced scale RC frame structures, representative of buildings with construction deficiencies in Pakistan. The models were subjected to the natural accelerogram of the 1994 Northridge earthquake and tested under multiple scaled excitations until the models attained incipient collapse state. The models’ damage mechanisms were studied, and the seismic response in terms of floor acceleration and floor displacement was retrieved. A uniform damage scale was developed for global performance assessment of considered deficient RC frames, listing average estimate of limit states’ drifts and base shear coefficients, with measured uncertainty, and describing frame damage condition. Numerical frame models were prepared in finite element-based program SeismoStruct and calibrated against experimental tests. The frames were analyzed through incremental dynamic analyses. Seismic fragility functions were derived using a probabilistic-based methodology, which may be used for global damageability assessment of the considered frame building typology. Available building damage-to-loss factors were employed to transform structural damages to repair cost ratio, which were correlated with seismic intensity (repair cost ratio versus seismic intensity) to derive the seismic vulnerability curve, which may be used for the direct economic loss estimation of the considered frame building typology.

Description: The intricate interplay between the microscopic constituents and their macroscopic properties for masonry structures complicates their failure analysis modelling. A composite strategy incorporating neural network (NN) and cellular automata (CA) is developed to predict the failure load for masonry panels with and without openings subjected to lateral loadings. The discretized panels are modelled by the CA methodology using nine neighbour cells, which derive their state values from geometric parameters and opening location placement for the panels. An identification coefficient dictated by these geometric parameters and experimental data is fed together as the input training data for the NN. The NN uses a backpropagation algorithm and two hidden layers with sigmoid activation functions to predict failure loads. This method achieves greater accuracy in prediction when compared with the yield line and finite elemental analysis (FEA) methods. The results attained elucidate the feasibility of the current methodology to complement conventional approaches such as FEA to provide additional insight into the failure mechanism of masonry panels under varied loading conditions.

Description: Dynamic and static coupling loads (DSLs) are one of the most common stress environments in underground engineering. As the depth of a roadway increases over the life of a mine, the static load of the ground stress field increase multiplies, and the cyclic operation at the working face releases a large amount of dynamic energy. Therefore, deep roadways easily induce dynamic disasters during production. In this paper, a deep roadway numerical model was built with FLAC3D to test the deep roadway under DSLs and was simulated with 16 different support designs. The ground stability in each support condition was examined and compared in terms of the ground deformation and scope of failure. The underlying support mechanism was further analyzed with numerical modeling in view of the deformation in the surrounding rock mass induced by variations in the support parameters. The results show that shortening the bolt spacing is an effective measure to control the deformation of surrounding rock whatever DSLs or static load. Under static load, the larger the anchoring length is, the more stable the surrounding rock is. Under DSLs, end grouting length (S = 600 mm) and full grouting length (S = 1800 mm) can effectively control the deformation of surrounding rocks and enhance the stability of surrounding rocks. The results contribute to the design of supports in the field of underground coal mines and provide a basis for determining the reasonable support scheme for roadways.

Description: Based on the maximum value of the self-stability of surrounding rock, the key issues affecting the distribution of the minimum mock cover thickness of the surrounding rock self-stability (MRCT-SRS) of the metro tunnel in the soil-rock dualistic stratum are discussed. The MRCT-SRS was studied for different soft stratum thicknesses Hs and excavation spans D based on cusp catastrophe theory. Moreover, the 3D spatial distribution was determined, and the fitted curves were constructed according to the MRCT-SRS, Hs, and D. This facilitated the assessment of the stability of the surrounding rock in the excavation of a metro tunnel. Combined with the construction practices used for the Qingdao metro project, the validity of the obtained MRCT-SRS has been verified by the inverse analysis of the monitored data from the metro tunnel. Furthermore, the application of the MRCT-SRS in determining the reasonable buried depth of a metro line has been explored. The research results have provided theoretical support and scientific basis for the preparation, revision, and improvement of the relevant codes, standards, and guidelines for metro tunnel planning and design.

Description: A standard stress path triaxial test system was applied to carry out conventional triaxial shearing tests for gravelly sands under confining pressures ranging from 50 kPa to 400 kPa at the initial relative densities of 0.15, 0.35, 0.55, and 0.75, respectively. The test results show that all the samples of gravelly sand present strain hardening and shear contraction during the process of shearing test. Additionally, gravelly sands are significantly affected by the initial relative density. The hardening degree of gravelly sand samples rises in line with increasing initial relative densities during shearing tests. When initial relative densities Dr are at 0.15 and 0.35, the volume shrinkage of samples decreases with the increasing confining pressures. Instead, when initial relative densities Dr are at 0.55 and 0.75, the volume shrinkage of samples increases with the growth of confining pressures. To describe these triaxial shearing mechanical properties of gravelly sands, a higher-order dilatancy equation was proposed based on the concept of a super yield surface. A constitutive model which can describe the mechanical properties of gravelly sand was established when the associated flow laws were applied to compare with the results of the triaxial shearing test under the consolidated drained condition. The comparison results showed that the proposed model can reflect the strain hardening and shear contraction characteristics of gravelly sands from low to high confining pressures under different initial relative densities.

Description: Passion fruit (Passiflora edulis (Sims)) is currently ranked third among fruit exports from Kenya and has great potential since the demand for both fresh fruit and processed juice is on a continuous increase. Passion fruit production in Kenya is constrained by a lack of healthy, clean planting material, poor seed viability, and low germination rates. To address this, the present study reports an in vitro plant regeneration protocol for passion fruit using leaf disc and nodal explants and genetic fidelity analysis of the regenerated plants. The highest number of shoot regeneration was obtained on Murashige and Skoog (MS) medium supplemented with 2 mg·L−1 6-Benzyl amino purine (BAP) (shoot induction medium). The multiplication of shoots was optimum in MS medium supplemented with 3 mg·L−1 BAP. To eliminate the requirement of an additional step of in vitro rooting, exogenous application of putrescine induced the formation and development of roots on nodal explants. Genetic fidelity analysis of the in vitro regenerated and macropropagated plants with that of the mother plant was carried out by sequence-related amplified polymorphism (SRAP) markers, and monomorphic banding profile for 80% of the regenerants confirmed the genetic uniformity of the in vitro regenerated and macropropagated plants. The in vitro regeneration system developed can be utilized for mass clonal propagation for the economic commercial exploitation of this important tropical fruit.

Description: The deformation rules and failure types of rock fatigue damage at different temperatures are quite different, and existing constitutive theory cannot describe them quantitatively. A novel rock fatigue damage model considering the effects of temperature was presented based on phenomenology. In this model, the residual strain method was used to define the fatigue damage, and the Harris attenuation function was introduced to characterize the cyclic damage evolution. The proposed model has considered the influence of the initial damage and temperature, and the model parameters can be easily calculated. The accuracy of the model was verified by comparing the calculated values of cyclic upper strain and fatigue life with previous test results. The physical significance of the model parameters shows that parameter a is related to fatigue stress ratio and lithology, while parameter b is related to temperature. The study has some reference values for the fatigue damage model of rock considering the influence of temperature.

Description: A series of tests were carried out to evaluate crack resistance and mechanical properties of polyvinyl alcohol fiber-reinforced cement-stabilized macadam, which is widely used as pavement base or subbase composite material. Three series of cement-stabilized macadam mixtures with cement content of 3.2%, 3.6%, and 4.0% were prepared by incorporating four various contents (0, 0.6, 0.9, and 1.2 kg/m3) and lengths (12, 18, 24, and 30 mm) of polyvinyl alcohol fiber. The optimum polyvinyl alcohol fiber content, fiber length, and cement content were determined based on the mechanical properties of cement-stabilized macadam mixtures. Then, unconfined compressive strength test, compressive resilience modulus test, splitting strength test, flexural tensile strength test, drying shrinkage test, and temperature shrinkage test were carried out in this study. The results show that polyvinyl alcohol fiber-reinforced cement-stabilized prepared by optimum proportions (cement 3.6%, fiber content 0.9 kg/m3, and fiber length 24 mm) has good crack resistance. The incorporation of polyvinyl alcohol fiber can effectively improve compressive strength and splitting strength, while its effect on CRM of cement-stabilized macadam is not remarkable. The anti-dry-shrinkage property and anti-temperature-shrinkage property of the specimens are also drastically improved due to the reinforcement effect of polyvinyl alcohol fiber. Moreover, the crack resistance index is proposed to evaluate the crack resistance of materials. The crack resistance of PVA fiber-reinforced cement-stabilized macadam prepared by optimum proportions is improved by 44.4%. Consequently, the mechanical properties and crack resistance of cement-stabilized macadam are obviously improved by adding polyvinyl alcohol fiber.

Description: In this work, a nonlocal strain gradient beam model considering the thickness effect is developed to study the nonlinear vibration response of a functionally graded nanobeam. The governing equation of the functionally graded nanobeam is derived by using the Euler–Bernoulli beam theory with von Kármán’s nonlinear strain-gradient relationship and the Hamilton principle. The expression of the nonlinear frequency for the functionally graded nanobeam with pinned-pinned boundary conditions is obtained with the help of Galerkin technique and the Hamiltonian approach. The obtained results show that the effect of thickness is very important for the size-dependent vibration response of the functionally graded nanobeam; the nonlinear vibration response of the nanobeam depends not only on the material length scale parameter and nonlocal parameter but also on the slenderness ratio. Effects of the slenderness ratio and the power-law index on the vibration response of the functionally graded nanobeam are also investigated and discussed. The numerical results show that the nonlocal parameter reduces the nonlinear frequency of the functionally graded nanobeam, while the material length scale parameter increases the nonlinear frequency of the functionally graded nanobeam. The slenderness ratio leads to an increase in the nonlinear frequency of the functionally graded nanobeam, while the power-law index leads to a decrease in the nonlinear frequency of the functionally graded nanobeam.

Description: The concrete expanded pile is a new type of pile in the field of foundation engineering, which exhibits improved performance compared to the ordinary straight-hole pile. The expanded technique increases the bearing capacity of the pile, changes the overall load-bearing function of the pile body, and offers great development prospects. While the performance of the expanded pile has been studied for vertical loading, the performance of expanded pile when subjected to horizontal loading is not adequately understood. In order to investigate the performance of concrete expanded pile in resisting horizontal loads, particularly the anti-overturning capacity of rigid and flexible piles, this paper conducts an experimental model test and performs a numerical simulation. In the experiment, an innovative model test method is used for testing small-scale half-face pile with undisturbed soil. A custom-made soil extractor and a loading device are used to observe various stages of pile-soil interaction in real-time during the whole process of loading. Meanwhile, finite element simulation analysis is conducted on a pile model and the corresponding data on displacement, load, stress, and strain are collected to verify the experimental results. Based on the horizontal bearing capacity of rigid and flexible piles and the failure states of soil mass around the piles, two calculation models are proposed for the horizontal bearing capacity of rigid and flexible concrete expanded piles. The models will provide reliable theoretical guidance for the application of concrete expanded pile in engineering applications and for the research and development of pile foundation.

Description: An experimental system for liquid nitrogen soaking and real-time temperature measurement was designed and implemented to investigate the characteristics of temperature field changes in coal under liquid nitrogen soaking. Then, the heat conduction law of the coal in the process of liquid nitrogen soaking and room temperature recovery for dry and water-saturated coal were examined. The microstructure characteristics of the coal before and after liquid nitrogen soaking were analyzed with nuclear magnetic resonance (NMR) technology. The results showed that, during the liquid nitrogen cold soaking process, the heat transfer law of the dry and water-saturated coal samples exhibited a notable three-stage distribution. For the room temperature recovery process, the dry and water-saturated coal samples exhibited rapid heating characteristics, and the cooling rate gradually decreased to zero. NMR test results indicated that the liquid nitrogen soaking increased the number of micro and small pores in the coal. Thermal stress analysis revealed that the thermal stress generated by the dry coal was larger than that produced by the saturated coal, and the damage was primarily caused by thermal stress. However, the permeability of the saturated coal was better than that of the dry coal. The damage on the saturated coal was caused by the volume expansion of pores and fissures caused by water-ice phase transition.

Description: With the development of tourism, the number of multistorey buildings in mountain areas is increasing gradually, and the requirements of the form and bearing capacity of foundation in landslide areas are getting more demanding than ever. In-situ testing of rock and soil mass in slope area has important practical significance for improving the stability of building foundation. Taking a project in Baishi Mountain located in southwest of China as an example, firstly, the geological structure and mechanical properties of soil are analyzed. Then, two types of pile foundations, i.e., empty-bottom pile foundations and solid-bottom pile foundations, are designed based on the characteristics of the geological structure for carrying out the static load test on pile foundation. The test results are as follows: (a) the load settlement curve (Q-S) of the empty-bottom test pile shows a steep drop, while the Q-S curve of the solid-bottom test pile shows a gradual change, showing that the end-bearing friction pile’s property and the ultimate bearing capacity of the solid-bottom pile are higher than those of the empty-bottom pile. (b) The maximum lateral friction of the four test piles is 139.158 kPa, 148.015 kPa, 150.828 kPa, and 154.956 kPa, respectively. (c) The shaft skin resistance under ultimate load is coming close to the maximum value, and the maximum values are 9.792 mm, 7.939 mm, 9.881 mm, and 14.97 mm, respectively. Research results can serve as design bases for the pile foundation of multistorey buildings located in landslide areas of Baishi Mountain in the southwest of China and also as references for the engineering application of pile foundation in similar geological fracture areas.

Description: The time-dependent behaviour of saturated soils under static and dynamic loading is generally attributed to the flow-dependent and viscous behaviour of pore fluid. However, the intrinsic energy dissipative effects from the flow-independent viscoelastic behaviour of solid skeleton are not always considered. In this study, the effect of flow-independent viscoelastic behaviour on the seismic amplification of ground soil in vertical and horizontal directions is studied based on a two-phase poroviscoelastic model. A generalized Kelvin–Voigt model is used to define the effective stress in the soils, and the compressibilities of both solid skeleton and pore fluid are considered. The seismic-induced dynamic displacements are analytically derived and are shown to depend on soil layer thickness, soil properties, and ground motion parameters. The formulation neglecting the viscoelastic behaviour of solid skeleton could overestimate both the vertical and horizontal motion amplifications at the surface of ground soil. In addition, the seismic responses of viscoelastic soils are demonstrated to be closely related to the saturation state of surface soil.

Description: The creep characteristics of soft clays have been studied for decades. However, the lateral deformation of soils is not allowed during the commonly used one-dimensional consolidation tests, which cannot describe the real deformation features of soils in practice. On the other hand, the influence of drainage distance on the mechanical properties of soil is still controversial, classified as hypothesis A and hypothesis B. For a better understanding of deformation characteristics of soft clay, especially which in long-terms, a series of conventional oedometer tests as well as novel geometric confined consolidation tests was conducted on soft dredger fill. The results show that the secondary consolidation coefficient of the soil sample Cα would increase firstly, followed by a small decrease with the increase of consolidation pressure generally. Cα would decrease with the consolidation time and also be reduced by preloading. The strain at the completion of primary consolidation would increase with the drainage distance, but the Cα would be affected little. Both compression index Cc and Cα of soft clay would reduce after preconsolidation, in which two parameters show an approximate linear relationship. The creep coefficient of soft clay under the geometric confinement Cαε k is larger than that under the oedometer test Cαε. However, the trends of the relationship between the creep coefficient and loading are consistent regardless of the confinement conditions.

Description: Nowadays, the electromechanical impedance method has been widely used in the field of structural healthy monitoring, especially for the concrete and steel materials. However, the electromechanical impedance studies on damage detection for timber are limited due to the anisotropic and ununiform biomaterial properties. As a low-cost and environment-friendly building material, timber has been widely used in the construction. Thus, it is beneficial to develop electromechanical impedance technique for structural healthy monitoring of timber so as to ensure the stability and safety of the entire timber structures. In this paper, two damage factors, i.e., the damage location factor and the damage size factor of timber specimens are investigated by using the electromechanical impedance method. The method is implemented by using a patch of Lead Zirconate Titanate transducer both as an actuator to generate stress waves and a sensor to detect stress waves after propagating across the timber specimens. Then, the damage index-root mean square deviation is employed to evaluate the damage severity of the timber specimens. The results indicate that the damage index changes consistently with the change of damage location and size factors, and the proposed method using electromechanical impedance technique can efficiently estimate the damage and its severity.

Description: The force-measuring rock bolt instrumented with bare fiber Bragg grating (FBG) sensors are generally factory-fabricated. To enable users to fabricate a force-measuring rock bolt by themselves, the microclamped FBG sensor is proposed to replace the encapsulated bare FBG sensor. A theoretical formula of strain sensitivity is also established. The strain sensibility measured by indoor calibration is consistent with the theoretical one, indicating that the microclamped FBG sensor can measure strain accurately. Besides, the measured strain sensibility coefficient (wavelength difference/strain) matches the theoretical values, making the installed microclamped sensor free from the need for recalibration and proving the installation method to be reliable. Also, the test sensitivity can be adjusted as needed. The instrumented rock bolt with microclamped FBG sensors shows great mechanical performance in the field test, awaiting further usage in applications.

Description: The project duration can be shortened by overlapping construction activities. However, the continuous changing of the environment tends to cause problems such as rework and the failure of the overlapping plan. In order to solve these problems, communication strategies for the overlapping of dependent activities are first introduced and optimized from a revenue perspective. We first consider the different maturities of upstream activity before and after the overlapping, the downstream sensitivity which is decided by involving communication strategies, and the learning and error-correcting ability of workers. Then, the overlap and communication strategies are decided by calculating the maximum revenue using Monte Carlo simulation and MATLAB based on overlap cost, communication cost, rework cost, and reward amount. Finally, the algorithm and BIM are combined to provide a visual overlap plan and dynamic control platform framework. This research is valuable for practitioners as it provides a dynamic overlap plan which can maximize the revenue in changing the environment and ensure the duration of the project. This research also provides researchers a new insight into combining overlap problems and BIM technology.

Description: The selection of seismic inputs for nonlinear dynamic analysis is widely debated, mainly focusing on the advantages and disadvantages provided by the choice of natural, simulated, or artificial records. This work proves the differences in the structural behavior of RC buildings when using accelerograms with different levels of stationarity. Initially, nonlinear response under three sets of accelerograms equivalent in terms of pseudo acceleration spectrum is evaluated and compared. Then, the results of incremental dynamic analyses are compared by the statistical point of view considering different levels of irregularity for the reference structure.

Description: It is highly important to clarify the high-temperature mechanical properties in the design of cold-formed steel (CFS) structures under fire conditions due to the unique deterioration feature in material properties under fire environment and associated reduction to the mechanical performance of members. This paper presents the mechanical properties of widely used steels for cold-formed steel structures at elevated temperatures. The coupons were extracted from original coils of proposed full annealed steels (S350 and S420, with nominal yielding strengths 280 MPa and 350 MPa) and proposed stress relieving annealed steels (G500, with nominal yielding strength 500 MPa) for CFS structures with thickness of 1.0 mm and 1.2 mm, and a total of nearly 50 tensile tests were carried out by steady-state test method for temperatures ranging from 20 to 700°C. Based on the tests, material properties including the yield strengths, ultimate strengths, the elasticity modulus, and the stress-strain curve were obtained. Meanwhile, the ductility of steels for CFS structures was discussed. Then, the temperature-dependent retention factors of yield strengths and elasticity modulus were compared to those provided by design codes and former researchers. Finally, a set of prediction equations of the mechanical properties for steels for CFS structures at elevated temperatures was proposed depending on existing tests data.

Description: A large-scale engineering procurement and construction (EPC) project is often conducted by a joint venture. Many factors affect the success of cooperation among participating enterprises, such as trust and the degree of effort of both parties. The most important one is a rational profit sharing mechanism. Reasonable profit sharing mechanism concerns whether the advantages of the EPC model can be fully utilized. In this study, the proposed EPC project is undertaken by a joint venture integrating design and construction enterprises. Moreover, the profit sharing problem arises from the project optimization implemented by both parties. The fairness concern behavior of both parties is considered, and the profit sharing model for the EPC project is established on the basis of game theory. The effect of the fairness concern behavior of both parties on the EPC project optimization and its profit sharing is further analyzed by simulation analysis. The research findings show that the project optimization profit and its sharing are related to not only the efforts and cost coefficient but also the fairness concern behavior of both parties. The research results are conducive to the application of the EPC model in the field of construction engineering.

Description: To investigate the uniaxial compressive strength and deformation properties of frozen silty soil with prefabricated crack under various strain rates, the static uniaxial compressive tests were conducted for frozen silty soil using three kinds of binder materials to select the suitable prefabricated crack manufacturing method. Afterward, the static and dynamic stress-strain curves of frozen silty soil with different prefabricated crack numbers were obtained based on static and splitting Hopkinson pressure bar (SHPB) tests. In addition, the high-speed camera was employed to record the fracturing process of frozen silty soil under impact loads. Results indicated that the frozen silty soil specimens with no binder showed higher static strength compared with other two binder materials (plaster and Vaseline). The strength growth rate of frozen silty soil showed three-stage (fast-slow-rapid) change characteristics. The peak strain of frozen silty soil under static loads scope was higher compared with that under dynamic loads, while its dynamic peak strain with various prefabricated crack numbers was remarkably rate-dependent. The absorbed energy density of frozen silty soil was subject to a negative (positive) relationship with the prefabricated crack numbers (strain rate). The dominated crack of intact frozen silty soil specimen finally presented Y-shaped shear failure. However, tensile cracks parallel to stress wave propagation direction were observed for the frozen silty soil specimen with prefabricated crack.

Description: The study investigates a new chemical grout by mixing the main agent, auxiliary agent, catalyst, foam stabilizer, solvent, and water, to treat the distress of railway tunnel. The orthogonal design was used to obtain 16 groups of grout proportion schemes, and reasonable proportion parameters were screened using laboratory and field tests. Additionally, this study included detailed research on the grout performance. The test results showed that the proportion schemes of groups 3, 4, and 15 grout were the most reasonable. In particular, for group 3, the viscosity is 663 MPa·s, the curing time is 119 s, the foaming capacity is 1589%, and the compressive strength is 20.16 MPa. For group 4, the viscosity is 663 MPa·s, the curing time is 137 s, the foaming capacity is 1809%, and the compressive strength is 17.76 MPa. For group 15, the viscosity is 281 MPa·s, the curing time is 98 s, the foaming capacity is 1173%, and the compressive strength is 26.79 MPa. Groups 4 and 15 grouts were used to treat the frost boiling and track bed subsidence in existed railway tunnels. Based on this, field monitoring showed that muddy water became clear water with an average depth of only 4 mm in the drainage ditch and that the irregular subsidence of the track bed was also solved after treatment. According to the aforementioned experimental research and analysis, it is proven that new grout not only exhibits a reasonable solidification time, high strength, and excellent waterproofing and impermeability with no pollution of the environment but also can be produced by a safe and convenient synthesis method. Group 4 is suitable for treating tunnel seepage, group 15 is suitable for structural reinforcement, and group 3 confers the advantages of seepage prevention, leakage stoppage, and reinforcement.

Description: An innovative method is proposed to prepare artificial columnar jointed rock masses (CJRM) with different columnar dip angles, and laboratory physical model tests are conducted to investigate anisotropic permeability and porosity characteristics of the prepared artificial CJRM. In the physical model experiment, permeability and porosity of artificial CJRM with different columnar dip angles is measured during three times cyclic loading and unloading of confinement pressure. Based on the results of the laboratory model tests, the Equivalent Continuum Media Model was applied to analyse anisotropic permeability of CJRM. The main conclusions are summarized as follows. In the first loading phase of confinement pressure, the impacts of confinement pressure on the anisotropic permeability of artificial CJRM, porosity, and the major and minor principle permeability coefficients (PPCs) are significant, while in the following stages of confinement pressure loading and unloading, the change of them is small, with stable value. Permeability of artificial CJRM gradually increases with rise of columnar dip angle, and the permeability anisotropy of artificial CJRM under low confinement pressure is higher than that under low confinement pressure.

Description: Rock bolts, one of the main support structures of the tunnel, can improve the stress state and mechanical properties of the surrounding rocks. The rock bolts are simulated by bar or beam elements in present numerical calculations for most 2D tunnel models. However, the methods of simulating rock bolt in three-dimensional models are rarely studied. Moreover, there are too many rock bolts in the long-span tunnel, which are hardly applied in the 3D numerical model. Therefore, an equivalent anchoring method for bolted rock masses needs to be further investigated. First, the jointed material model is modified to simulate the anisotropic properties of surrounding rock masses. Then, based on the theoretical analysis of rock bolts in reinforcing mechanical properties of the surrounding rock masses, the equivalent anchoring method of the jointed rock mass tunnel is numerically studied. The equivalent anchoring method is applied to the stability analysis of a diversion tunnel in Western China. From the calculation results, it could be found that the reinforcement effect of rock bolts could be equivalently simulated by increasing the mechanical parameter value of surrounding rocks. For the jointed rock mass tunnel, the cohesion and internal friction angle of the surrounding rocks are improved as 1.7 times and 1.2 times of the initial value, which can simulate the reinforcement effect of rock bolts. Comparing with analytical results, the improved internal friction angle is nearly consistent with analytical result. The reinforcement effect of rock bolts is simulated obviously when the mechanical parameters of surrounding rocks are increased simultaneously. The engineering application shows that the equivalent anchoring method can reasonably simulate the effect of rock bolts, which can provide reference for stability analysis of three-dimensional tunnel simulations.

Description: This paper presents a case history of the developmental effect of a large-area excavation, 8 high-rise main buildings, a series of annex constructions, and ground overloaded building demolition on the deformation characteristics of an existing shield tunnel within Guangzhou Metro Line No. 1 in close proximity to the development. The shield tunnel lies in a sandy layer of the typical upper-soft and lower-hard strata in Guangzhou district, and the deformation of the tunnel has been monitored since the tunnel was put into operation. The monitoring results reveal that the adjacent construction induces an excessive tunnel settlement with a maximum of 14.4 mm and an excess tunnel displacement with a maximum of 5.2 mm, which are within the corresponding limitations of the codes for the safe operation of urban rail transit tunnels. While the station expansion project is being conducted beside the tunnels, a series of tunnel distresses, including large-area water seepage, spalling concrete blocks, and segmental cracks, are recorded. Our field monitoring data indicate that the tunnel is subjected to further vertical contraction and horizontal expansion due to the station expansion project, and a maximum tunnel flattening rate of 36.78% is detected. Furthermore, the tunnel linings are studied numerically and theoretically to obtain the limitations of tunnel deformation and discuss why tunnel distresses of water seepage, concrete spalling, and segmental cracking occur. Finally, on the basis of the analyses and discussions above, counteracting corrective measures, including compensation grouting soil strengthening and bonded steel plates, are adopted as exterior and interior strengthening methods, respectively, to eliminate further tunnel distresses and ensure safe operation. The lessons learned and summarized in this study may help prevent similar tunnel distresses from reoccurring in the future.

Description: In order to reduce the foundation settlement, conserve resources, and be environmental-friendly while increasing the use of soil resources, an artificial crust layer formed by in situ stabilization is proposed to combine with prestressed pipe piles over soft ground in road construction. In this study, a centrifuge test and two-dimensional coupled-consolidation finite-element analyses are conducted to simulate the construction of an embankment. And a two-dimensional parametric study is conducted to study the performance indicated by maximum long-term settlement, excess pore water, and tensile stress under various conditions. The results of the centrifuge test clearly show that the measured settlement, excess pore water, and tensile stress are in good agreement with the calculated results. In addition, the key factors of pile spacing and thickness and strength of the crust have an influence on the maximum settlement, stress of the foundation, and tensile stress of the crust using the two-dimensional coupled-consolidation finite-element analyses. And the stress transfer regular of the foundation is analyzed under various conditions. Moreover, the failure of the crust contained tensile cracking and shearing failure and the thickness of the pile that pierced the crust are also affected by the key factors.

Description: In practical engineering, if the influence of noncoaxial stress and strain is not considered, part of soil deformation will be ignored, resulting in the structural design which is not safe enough. A series of undrained tests was performed on remolded loess specimens using a hollow cylinder apparatus to examine the coupling between principal stress magnitude and direction in these specimens. First, the elastic parameters of remolded loess were obtained, and these parameters were used as the basis for investigating the noncoaxiality of the soil body under principal stress axis rotation (PSAR). The effects of elastic strain, intermediate principal stress coefficient, and magnitude of the deviatoric stress on the noncoaxiality of remolded loess were also investigated. The results of these experiments show that remolded loess exhibits significant noncoaxial behavior during PSAR. The noncoaxiality angle of remolded loess cyclically fluctuates with increases in the principal stress angle. It was also observed that the noncoaxiality angle will be overestimated if the effects of elastic strain are overlooked. Reversals in the direction of PSAR cause dramatic changes in the noncoaxiality angle. Increases in the intermediate principal stress coefficient are accompanied by increases in the noncoaxiality angle, up to a certain degree; however, these changes do not affect the development of the noncoaxiality angle. In coupled rotational tests with a range of deviatoric stress amplitudes, it was observed that changes in the deviatoric stress amplitude will affect the development of the noncoaxiality angle; increases in the deviatoric stress amplitude cause the noncoaxiality angle versus principle stress angle plot to shift to the left gradually, thus accelerating the trends of the noncoaxiality angle. Increases in the cycle number also increase the noncoaxiality of remolded loess.

Description: The additional damping ratio (ADR) is an important indicator for evaluating the damping effect of structures with energy-dissipation devices. Most existing methods for determining the ADR require an analysis of the structural dynamic response and complex iterative calculations. An innovative simplified calculation method for determining the ADR of a structure supplemented by nonlinear viscous dampers is proposed. This method does not require the dynamic response of the structure to be calculated and only requires the structural characteristics, excitation frequency, and damper parameters. In this study, several typical calculation methods for the ADR were analysed. Then, a calculation formula for the ADR was derived with consideration of harmonic excitation under the condition where the excitation frequency is equal to the structural natural frequency, without calculation of the structural dynamic response or an iterative process. The effect of the excitation frequency on the calculated value of the ADR with different damping exponents was studied. Accordingly, the response spectrum average period (RSAP) was considered as the excitation period of ground motion to evaluate the excitation frequency, and a simplified calculation method for the ADR considering the effect of the excitation frequency characterised by the RSAP of the ground motion was established. Finally, the accuracy and effectiveness of the proposed method were verified by comparison with ADRs calculated using other methods.

Description: Coral mud, a kind of special material used for constructing islets in reclamation projects, is widely spread in the South China Sea. Combined with microstructure research, a series of triaxial tests were performed in this paper to study the static shear strength characteristics and potential factors that can influence them. The effective stress path was similar to the total stress path because of the unique microstructure resulting in a high strength and a high dissipation rate of the pore pressure in the coral mud. The initial void ratio and the initial confining pressure affected the strength and deformation characteristics of the coral mud. When the soil came to failure, the pore pressure coefficient Af varied linearly with the initial void ratio. The critical friction angle was greatly influenced by the confining pressure, and its magnitude first developed to a peak value and then decreased as the void ratio increased. This change showed that there was a linear relationship between the initial elastic modulus E0i and lgp0 as well as between the secant modulus E50 and p0. The estimation ability of Cam-Clay was verified in this research. The value of parameter λ was determined incrementally by a larger initial void ratio, while the value of parameter M decreased smoothly first and then rose slightly; the selection of parameter κ was approximately 0.0035. The results supported that the Cam-Clay model is able to simulate the stress-strain relationship of coral mud, and a referenced estimation can be reliably and efficiently obtained for the reclamation projects of constructing islets.

Description: The mechanical property of jointed rock mass is an important factor to be considered in the analysis, evaluation, and design of actual rock engineering. The existence of joints threatens the stability and safety of underground engineering projects built in the rock mass. In order to study the change of mechanical properties and strength characteristics of nonpenetrating jointed rock mass under different test conditions, direct shear tests and triaxial tests were carried out. Direct shear tests under different normal stresses were carried out for nonpenetrating jointed rock mass to prepare specimens for triaxial tests. Then, triaxial tests were carried out to study the change of mechanical properties and strength characteristics of the nonpenetrating jointed rock mass. In the direct shear test part, the greater the normal stress is, the stronger the shear strength and the more serious the shear failure would be. The main conclusions are as follows: (1) the strength of rock mass would increase with the increase of confining pressure for those rock specimens with same degrees of shear after the direct shear test; (2) for rock specimens with different degrees of shear after the direct shear test, if the shearing degree of the rock specimen was greater, the strength of the rock specimen would be lower in the triaxial test; (3) for rock specimens with the same damage degree after direct shear test, the greater the normal stress in direct shear test is, the smaller the peak axial pressure would be in the triaxial test; (4) if the specimen was sheared under higher normal stress in direct shear test, the cohesion of it would be lower and the internal friction angle would be larger. For the specimens under the same normal stress, if the shear failure of one specimen was more serious, the cohesion of it would be smaller and the internal friction angle would be larger.

Description: This research aimed to address health and food security challenges affecting Los Angeles and beyond in our own backyard. One possible way to combat these challenges is through biotechnology. The purpose of this research was to characterize the arable soils at Los Angeles Pierce College and their potential uses. The methods employed were collection of soil physical and chemical properties, cultivation of soil microorganisms, and 16S rDNA sequencing with a citizen science platform. Statistical analysis in R revealed associations between field conditions and life in the soil. The testing of plant-based antimicrobial agents on antibiotic-resistant bacteria revealed that plant oils could be more efficacious for control than common antibiotics. We found evidence of plant growth-promoting, antibiotic-producing, and bioremediating bacteria in different fields with distinct microclimates based on the 16S rDNA taxonomy results and inferred functional profiles. The major findings included an abundance of Streptomyces, Bacillus, Methylobacteria, and others with desirable functions. Numerous Streptomyces isolates cultivated on selective media demonstrated the ability to reduce nitrate. These results will empower future trials and product development by identifying target soil microorganisms and the most viable fields.

Description: Both numerical simulations and data-driven methods have been applied in dam’s displacement modeling. For monitored displacement data-driven methods, the physical mechanism and structural correlations were rarely discussed. In order to take the spatial and temporal correlations among all monitoring points into account, we took the first step toward integrating the finite element method into a data-driven model. As the data-driven method, we selected the random coefficient model, which can make each explanatory variable coefficient of all monitoring points following one or several normal distributions. In this way, explanatory variables are constrained. Another contribution of the proposed model is that the actual elastic modulus at each monitoring point can be back-calculated. Moreover, with a Lagrange polynomial interpolation, we can obtain the distribution field of elastic modulus, rather than gaining one value for the whole dam in previous studies. The proposed model was validated by a case study of the concrete arch dam in Jinping-I hydropower station. It has a better prediction precision than the random coefficient model without the finite element method.

Description: In order to quantitatively investigate the energy dissipation characteristic during the dynamic tension failure of rock materials, the dynamic Brazilian disc tests on red sandstone were conducted using the split Hopkinson pressure bar (SHPB) setup. The states of the specimens after different incident energies can be divided into three forms (i.e., the unruptured state, the ruptured state, and the broken state), and the failure processes of the specimens were recorded by using a high-speed camera. The results show that the ruptured state of the specimen corresponds to the critical failure strain. Taking the critical incident energy as a turning point, two positive linear fitting relations between the dissipated energy and incident energy before and after the point are obtained, and the dynamic linear dissipation law is found. When the incident energy is less than the critical energy, specimens were unruptured after impact. When the incident energy is greater than the critical energy, specimens will be broken after impact. According to the obtained linear energy dissipation law, the dynamic tensile energy dissipation coefficient (DTEDC) was introduced for quantitatively describing the dynamic energy dissipation capacity of rock materials in the dynamic Brazilian disc test. When the specimen is in the unruptured state, the ideal DTEDC is a constant value. When the specimen is in a broken state, the DTEDC increases with the increase of incident energy.

Description: Soil conservation practices such as cover crops can improve crop production, soil quality, and water quality. Cover crops can also influence soil microbial growth and activity. Cover cropped and manured soils can potentially store and transmit fecal bacteria (e.g., E. coli) to surface water if runoff and subsurface seepage occur. While many studies have shown the soil health benefits of cover crops, fewer studies have evaluated the extent to which cover crops influence the abundance of potential waste-borne pathogens. A two-year study (2015–2017) was conducted on a limited-resource farm in Logan County, Kentucky, USA, to quantify the abundance of the fecal indicator Escherichia coli (E. coli) bacteria (as a proxy for fecal coliforms) in treatments with and without cover crops or composted poultry litter. The cover crop consisted of a cereal rye (Secale cereale L.), Austrian winter pea (Pisum sativum L.), and crimson clover (Trifolium incarnatum L.) mix. Summer crops consisted of a no-till maize (Zea mays L.)—soybean (Glycine max L.) rotation. Soil samples were taken before and after each summer crop season and assessed to detect and enumerate E. coli. At the end of the study period, no significant treatment differences in the E. coli abundance in soil were detected (ca. 104 CFU·g−1) (). However, season/time was a significant factor (). We conclude that the background E. coli already present in soil was sufficiently high, inhibiting the detection of the influence of added composted litter. These indigenous E. coli were unaffected by cover crop and nutrient management but did fluctuate on a seasonal basis.

Description: Seven field trials were completed over a three-year period (2016 to 2018) in southwestern Ontario, Canada, to assess weed control in conventional-till dicamba-resistant (DR) soybean with glyphosate/dicamba (2 : 1 ratio) applied postemergence (POST) at 3 doses (900, 1350, and 1800 g·ae·ha−1) and 3 application timings (up to 5, 15, and 25 cm weeds). There was minimal soybean injury (≤2%) from treatments evaluated. Glyphosate/dicamba applied at application timing of up to 5, 15, and 25 cm weeds, controlled Amaranthus spp. (pigweed spp.) 87–96, 94–99, and 99%; Ambrosia artemisiifolia (common ragweed) 93–99, 97–99, and 99–100%; Chenopodium album (lambsquarters) 89–99, 95–100, and 99–100%; Echinochloa crus-galli (barnyardgrass) 81–84, 94–96, and 96–97%; Setaria faberi (giant foxtail) 37–90, 77–98, and 99–100%; and Setaria viridis (green foxtail) 94–96, 99, and 99–100%, respectively. Additionally, glyphosate/dicamba applied POST at 900, 1350, and 1800 g·ae·ha−1 controlled Amaranthus spp. 90–97, 95–98, and 97–99%; A. artemisiifolia 95–98, 97–99, and 99–100%; C. album 92–99, 95–100, and 98–100%; E. crus-galli 84–88, 93-94, and 95-96%; S. faberi 74–95, 75–97, and 79–98%; and S. viridis 98, 98–99, and 98–100%, respectively. Weed interference reduced DR soybean yield as much as 51% compared to the highest yielding treatments. Results indicate that glyphosate/dicamba applied POST at the label doses can provide an adequate control of troublesome weeds in DR soybean. Weed control was generally most consistent when glyphosate/dicamba was applied at the highest registered dose in Ontario (1800 g·ae·ha−1) and when weeds were up to 25 cm tall.

Description: This study compared the effects of shading in individual branch orders 2 and 3 on the needle survival, growth, and reproduction of five categories of short shoots of the proximal part of wild Atlas cedar (Cedrus atlantica (Endl.) G. Manetti ex Carrière). The sun exposure did not affect the number of short shoots in the two branch orders, whereas light compared to shade only stimulates the unbranched short shoot elongation of the branch order 3. The impact of shade exposure compared to sun on the loss of needles depends on the order of branching; it is weak to order 2 and increases to higher order. This effect in the branch order 3 is achieved by a significant decrease of the fallen leaf number in the unbranched short shoot SSnr and the short shoot SS/T worn by Twigs while in the branch order 2 only short shoot SS (nr + r) loses significantly few needles. In terms of short shoot extension and needle loss, the SS/T of the branch order 3 behaves in the same way as the SS (nr + r) of the branch order 2. The shadow compared to sunlit only decreases significantly the production of pollen strobili of the branch order 2. Close relationships between short shoot extension, leaf life span, and pollen strobili production of axillary products in the proximal part of C. atlantica crown were found.

Description: As an effect of intensive agricultural development of the steppes of the northern Black Sea coast, the finds of postantique agricultural landscapes that preserve relic elements of ancient land-use infrastructure are extremely rare. To these belongs the uniquely preserved ancient Greek land division system on the Tarkhankut Peninsula (north-western Crimea), which was studied using the methods of soil science and biomorphic analysis. This paper explores ancient land-use practices in order to reconstruct the original parameters of the land division system, as well as agricultural techniques employed. For postantique agricultural landscapes, an integrated geoarchaeological approach that includes GIS and remote sensing methodologies, in-field study of microrelief and soil registrograms, pedochronological dating technique, and physicochemical, geochemical, and biomorphic soil analyses has been developed and tested. The soil-geomorphological reconstruction shows that the Hellenistic land division system included a 4.5–4.9 m wide strip of land bordered by a 4.1–4.7 m wide (at the base) and c. 0.2 m high wall and a c. 2 m wide and over 15 cm deep trench, which controlled surface runoff and erosion. Ancient agricultural practices of slope farming resembled the modern ones. Surface runoff and soil erosion were controlled by dividing the catchment area into narrow plots, the borders of which on arable land were marked by simple earthen structures (low walls with shallow trenches). The biomorphic analysis of soil sampled atop these structures indicates that in ancient times, these earthen walls were not cultivated. The study of conservative properties preserved in pedomemory of postagrogenic soils provided valuable evidence of agricultural techniques used in the palaeogeographic conditions of the 4th and 3rd centuries BC.

Description: Production of pearl millet with yield improvement would have a direct impact on the drought-prone areas of Ethiopia since pearl millet is drought tolerant and early maturing with high water use efficiency. An experiment was conducted to study the performance of pearl millet under different technologies in 2013 and 2014 main cropping seasons at the main site of the research center, Aybra, with the objective of evaluating and identifying appropriate combinations of technologies that enhance the production of pearl millet in the study area. About fourteen integrated technologies were applied in a randomized complete block design with three replications. The analysis was done by using SAS software version 9.1, and means were separated through the Duncan multiple range test. Results of analysis of variance showed that yield-related traits of pearl millet were significantly influenced by the integration of technologies in the 2013 cropping season. According to the results, the maximum yield (3084 kg ha−1) was recorded with the application of the treatment combination of recommended fertilizer application + seed primming + tie ridging, while the minimum was recorded (919 kg ha−1) in the treatment combination of microdose application of fertilizer + primed seed + intercropping of pearl millet with mung bean. In the case of the 2014 cropping season, the highest grain yield (3687 kg ha−1) was recorded with the treatment combination of microdose fertilizer application + primed seed + tie ridging + intercropping of pearl millet with mung bean, whereas the lowest grain yield (2115 kg ha−1) was recorded in the treatment combination of no fertilizer application + primed seed + flat bed. Based on the results of the current investigation, it could be recommended that using technology integration of microdose, tied ridge, primed seed, and intercropping of pearl millet with mung bean is better to attain maximum yield in the study area and similar agroecologies.

Description: Land degradation is a global negative environmental process that causes the decline in the productivity of land resources’ capacity to perform their functions. Though soil and water conservation (SWC) technologies have been adopted in Geshy subcatchment, their effects on soil quality were limitedly studied. The study was conducted to evaluate the effects SWC measures on soil quality indicators in Geshy subcatchment, Gojeb River Catchment, Ethiopia. A total of 54 soil samples (two treatments–farmlands with and without SWC measures  three slope classes  three terrace positions  three replications) were collected at a depth of 20 cm. Statistical differences in soil quality indicators were analyzed using multivariate analysis of variance (ANOVA) following the general linear model procedure of SPSS Version 20.0 for Windows. Means that exhibited significant differences were compared using Tukey’s honest significance difference at 5% probability level. The studied soils are characterized by low bulk density, slightly acidic with clay and clay loam texture. The results revealed that farmlands with SWC measures had significantly improved soil physical (silt and clay fractions, and volumetric soil water content (VSWC)) and chemical (pH, SOC, TN, C : N ratio, and Av. phosphorus) quality indicators as compared with farmlands without SWC measures. The significantly higher VSWC, clay, SOC, TN, C : N ratio, and Av. P at the bottom slope classes and terrace positions could be attributed to the erosion reduction and deposition effects of SWC measures. Generally, the status of the studied soils is low in SOC contents, TN, C : N ratio, and Av. P (deficient). Thus, integral use of both physical and biological SWC options and agronomic interventions would have paramount importance in improving soil quality for better agricultural production and productivity.

Description: Decomposition is a key flux of terrestrial carbon to the atmosphere. Therefore, gaining a better understanding of how plant litter decomposes in soil, and what governs this process, is vital for global climate models. The Tea Bag Index (TBI) was introduced by Keuskamp et al. (2013) as a novel method for measuring litter decomposition rate and stabilisation. The TBI uses two types of tea bags representing fast (green tea) and slow (rooibos tea) decomposition substrates as standardised litter bags. To date, the TBI method has been used in over 2000 locations across the globe. However, before now, there has been no information on how the composition of the tea leaves change during incubation. These data are crucial in determining the validity of the use of the TBI method globally, to ensure the tea leaves decompose in a way that is representative of so-called “native” litters. To provide chemical underpinning of the TBI method, a laboratory incubation of the tea bags was conducted with destructive sampling at 0, 7, 14, 21, 28, 35, 42, 49, 56, 63, 70, 77, 84, and 91 d. The incubated tea was analysed for total C and N. In addition, C was characterised as alkyl, O-alkyl, aromatic, or carbonyl C using solid-state 13C nuclear magnetic resonance spectroscopy with cross-polarization and magic angle spinning (CPMAS NMR). The results suggest that changes in carbon in both tea types are comparable to other litter studies, with a net decrease in total C and relative proportion of O-alkyl C fraction, which contains carbohydrates and cellulose. We conclude that the decomposition of tea leaves in the bags used in the TBI is representative of other litters.

Description: Soil loss triggered by water erosion constitutes a major issue that causes several environmental and socioeconomic concerns. The Moroccan Western High Atlas is the most vulnerable area in the High Atlas Mountains, due to the existence of different forms of landslides, and evidences of erosion are widely observed. This study aims at estimating and quantifying the amount of soil loss as well as highlighting potential areas to erosion risk, using the Revised Universal Soil Loss Equation (RUSLE) combined with GIS and remote sensing. The RUSLE model provides a possibility of computing erosion susceptibility for each pixel on the basis of the controlling factors which are rainfall aggressivity, topography, vegetation cover, soil erodibility, and support practices. In this study, results show that the erosion rate varies between 0 and 227.67 t/ha/year, with an average annual soil loss of 40.38 t/ha/year, and the Beni Mohand River basin is subject to very high rates of erosion which can be irreversible since it exceeds the tolerable standard rate which is 1 t/ha/year. These findings will provide land use planners baseline for land use and risk management and will provide data within the Moroccan Western High Atlas Mountains.

Description: Masonry structures are widely used in developing countries due to their low cost and simple construction, especially in remote areas, where there are a large number of houses without seismic measures. These buildings are prone to collapse and cause a lot of casualties, even under the action of small earthquakes. For the reinforcement of this structure, a cheap, effective, and easy-to-construct reinforcement method is urgently needed. Therefore, this article studies the reinforcement method of polypropylene bands (PP-bands). We have carried out low-frequency cyclic loading tests for two PP-band reinforced masonry walls and two compared masonry walls. We mainly studied the influence of PP-band and different compressive strengths of plastering mortar on the masonry wall’s seismic capacity. The seismic indicators mainly studied in this article include ultimate bearing capacity, energy dissipation capacity, stiffness degradation, and hysteresis characteristics. The experimental results show that the PP-band can greatly enhance the seismic capacity of the masonry wall. The ultimate bearing capacity, energy dissipation capacity, and displacement ductility of the PP-band reinforced wall are increased by 38%–48%, 22%–47%, and 138%–226%.

Description: The instability of reservoir slope is likely to cause some severe natural hazards such as surge and barrier lake. In this study, the changes in seepage field and the distribution of the unsaturated zone of a reservoir bank slope subjected to rapid water-level fluctuations are investigated using the finite element method. The stability analysis of a reservoir slope under water-level fluctuation with a rate of 2 m/day is performed. The stability analysis is based on the theory of unsaturated soil mechanics and saturated-unsaturated seepage and accounts for the hydromechanical coupling effect. The changes in shear stress and strain as well as pore water pressure due to rapid water-level fluctuations are explicitly examined. Furthermore, the stability factor of safety, the underlying failure mechanism, and relevant influence factors are discussed. Based on the finite element analysis, it is found that the rapid loss of matrix suction would give rise to the surface landslide near the slope toe.

Description: The rock-breaking characteristics and the influence factors of laser perforation are investigated in this study. A series of fiber laser perforation experiments on basalt, sandstone, and granite were conducted. Experimental measurements of rock failure morphologies and composition tests showed that the main surface features are thermal cracks and glazed layer formed by the melting and condensing of rock in laser perforation. It is also found that higher quartz content could help reduce the glazed degree of rock. Comprehensive results showed that the laser rock perforation is mainly formed by thermal fractures, the decline of molten pool, and the evaporating and splashing of the special melted rock components. The depth of rock perforation and SE usually increase with the laser irradiation time, while the ROP gradually decreases. With the increase of laser power, the perforation depth and ROP gradually increase, while the SE initially decreases and then increases indicating that there is an optimal power that maximizes perforation efficiency. It is believed that the strength of rock is the main factor affecting laser perforation efficiency, and the lower rock strength resulted in deeper perforation depth, higher ROP, and lower SE.

Description: LEDs are widely applied in highways and tunnels for their long life, low light attenuation, and being environment friendly in recent years. The influence of correlated color temperature (CCT) of LED on lighting safety has attracted people’s attention as the demand increased. In this paper, a calculation model of perception luminance of human eye considering mesopic vision and fog concentration was proposed. The influence of different CCTs on perception luminance of human eye under different levels of fog concentration and luminance was calculated and analyzed. The CCT of LED employed in the interior zone of a tunnel was selected based on the highest perception luminance in mesopic vision. Seven kinds of LEDs with different CCTs (3000–6500K) were applied in the experimental system with adjustable fog concentrations. The results showed that the main factors affecting visual perception are luminance and fog concentration. Higher luminance or lower fog concentration provides drivers with higher perception luminance. In contrast, although CCT has a less effect on perception luminance, LEDs with higher CCT (about 6500K) can provide higher perception luminance considering fog in mesopic vision. This paper provides technical support for tunnel lighting and guaranteeing traffic safety.

Description: Understanding cultivar responses to a new herbicide is crucial to determining appropriate herbicide use and management practices. Florpyrauxifen-benzyl is a new rice herbicide developed to control troublesome weeds in rice production. Little research has been conducted to characterize rice cultivar responses to florpyrauxifen-benzyl, and thus, a field experiment was conducted at the Pine Tree Research Station (PTRS) in 2017 and 2018 and at the Rice Research and Extension Center (RREC) in 2018 to determine rice cultivar tolerance to florpyrauxifen-benzyl as influenced by herbicide rate, the addition of imazethapyr, and rice growth stage. Another experiment was conducted in 2018 at PTRS and RREC to assess crop response when florpyrauxifen-benzyl at different rates is applied with and without malathion, a known cytochrome P450 inhibitor. Three cultivars were evaluated in both experiments: a long-grain variety “CL111,” a medium-grain variety “CL272,” and a long-grain hybrid “CLXL745.” Injury in the first experiment was higher when florpyrauxifen-benzyl was applied at 60 g ae ha−1 than at the labeled rate of 30 g ha−1, with the most injury being 10% when averaged over growth stage at the time of application. Generally, applications made at the 3-leaf growth stage resulted in the most injury; however, this injury was at most 14%. Additionally, there was no reduction in grain yield for any cultivar, indicating florpyrauxifen-benzyl can be used safely in conjunction with imazethapyr in imidazolinone-resistant rice. In the second experiment, there was no more than 10% injury and no reduction in grain yield, with the addition of malathion not causing an increase in rice injury. Results from these experiments indicate florpyrauxifen-benzyl can be mixed with imazethapyr and the addition of malathion will not lead to increased risk for injury to rice.

Description: Improved nitrogen use-efficient cultivars could be the most economically beneficial and environmentally friendly approach to reduce pollution associated with excessive N fertilization. The performance and genetic gain in grain yield and nitrogen use efficiency (NUE) of a historical set of 12 bread wheat cultivars released for a heat-stressed environment were investigated at four N levels (0 (N0), 43 (N43), 86 (N86), and 129 (N129) kg/ha) for two seasons. Averaged across seasons, increasing N level from N0 to N43, N86, and N129 resulted in yield increases ranging from 4−45%, 13–69%, and 34–87% at N43, N86, and N129, respectively. These yield increases were associated with increases in biomass (r = 0.86, P

Description: The study was carried out at Entoto Mountain and its surrounding area, about 10 km north of the center of Addis Ababa. The purpose of this study was to assess the floristic composition and regeneration status of woody species and recommend further conservation methods. Ten transect lines were laid from south-north at 1 km interval. Along these transect lines, 62 sample plots of 400 m2 (20 m × 20 m) were laid at 1 km interval. A total of 179 plant species belonging to 107 genera and 60 families were recorded. Asteraceae (30 species) was the most dominant family. Of 179 plant species, 73 were naturally regenerated woody species representing 48 genera and 34 families. Herbs account for the largest growth form (91, 50.84%), indicating the fact that disturbance favors herb species. For the analysis of vegetation diversity, woody species composition, and density, the study area was classified into five land-use types. Of the five land-use types, degraded land-use type had low species diversity and evenness (1.48 and 0.295), and it had a low density of economically and ecologically important larger trees. However, the density of seedlings and saplings showed the normal regeneration status for the herbs and shrubs. Therefore, responsible stakeholders should give high priority for the conservation of ecologically and economically important large trees using appropriate conservation methods in the study area.