ALBERT

Description: This article contains the analysis of the correlation between the cone resistance qc from CPTU tests and shear modulus G0 determined from seismic tests SDMT and SCPTU. The analysis was performed for sands located in Poland, characterised by differential grain size distribution and origin. The significant impact of the independent variables; grain size, preconsolidation stress σ’p , geostatic vertical stress σ’v0 and relative density index on the dependencies analysed, were examined in three stages. Firstly, a general relationship between the cone resistance and shear modulus G0 was established; in the second stage, an analysis was carried out in selected groups of subsoil; and in the third stage, the influence of other independent variables was taken into account. In each stage, the functional form of the dependency was determined, and their statistical significance was assessed throughout coefficient of determination R2. For more variables, multivariable regression analysis was applied for assessment. Conducted analysis showed that the overall view of the relation between the cone resistance qc and shear modulus G0 has low evaluation of the statistical significance. This fact is consistent with the theoretical assessment of this relationship. To obtain a satisfactory assessment of this dependency, it is necessary to construct empirical equations for individual groups of soil, taking into account other independent variables; preconsolidation stress σ’p , vertical stress σ’vo and relative density index. This approach allows to assess the local correlation relationship, which is very useful during the geological project.

Description: The paper concerns the characteristic parameters of the selected isotropic failure criteria, i.e. Mohr–Coulomb, Drucker–Prager, Matsuoka–Nakai and Lade–Duncan. The parameters are determined directly from the failure criteria and stress measurements or by semi-theoretical approach, assuming that the soil obeys the associated flow rule and using the plane strain condition. In the latter case, the parameters can be expressed as functions of the plane strain internal friction angle, which is determined from measurements. The principal stress tensor components, corresponding to the soil peak strength and necessary to obtain the failure criteria parameters, are measured in a series of true triaxial, plane strain tests, on coarse Skarpa sand samples of different initial relative density, subjected to various confining pressures.

Description: In this paper, a qualitative safety analysis of the Żelazny Most tailings pond is addressed. This object is one of the largest facilities of this type in the world being a crucial element in the technological line of copper production in KGHM Polska Miedź S.A. The assessment of the effectiveness of two types of preventive measures, i.e., relief wells and loading berms, is investigated based on displacement and stability analysis of two 2D cross-sections in a technical section of the dam. The study shows that the considered preventive measures generally have a positive impact on increasing the safety level of the structure during its further raise. In particular, their effectiveness is most evident when they are applied simultaneously. It is eventually suggested that the selection of final solutions to be applied on the facility should be based on the quantitative 3D analysis.

Description: Tests that were carried out in order to obtain knowledge of the actual values of strength parameters obtained by CIPP liners that are used to repair pipelines. Specimens of liners made of high quality polyester felt cured with epoxy resin were subjected to tests. The scope of the performed studies corresponded with the scope of acceptance tests, which are carried out in the investment process during quality control of renovation works. Specimens of liners taken from sewers with 3 different diameters, i.e. 200mm, 350mm and 500mm were selected as representative for underground sewage networks. The obtained results enabled the calculations carried out in the course of design work to be verified, and differences between the model values of the strength parameters obtained from the calculations, and real values that are burdened with irregularities resulting from the conditions prevailing at a construction site and which were obtained for specimens taken from their built-in locations to be compared. The tests confirmed that it is possible to renovate - using CIPP liners - sewers with a lot of structural and material damage that negatively affects a liner‘s geometry. The implementation of the reinforcing internal coating in a sewer enables its further safe operation. The direct application value of the research involves the enlargement and clarification of knowledge concerning the actual load-bearing capacity of CIPP liners.

Description: This study presents the behaviour of model footing resting over unreinforced and reinforced sand bed under different loading conditions carried out experimentally. The parameters investigated in this study includes the number of reinforced layers (N = 0, 1, 2, 3, 4), embedment ratio (Df /B = 0, 0.5, 1.0), eccentric and inclined ratio (e/L, e/B = 0, 0.05, 0.10, 0.15) and (a = 0°, 7°, 14°). The test sand was reinforced with bi-axial geogrid (Bx20/20). The test results show that the ultimate bearing capacities decrease with axial eccentricity and inclination of applied loads. The test results also show that the depth of model footing increase zero to B (B = width of model footing), an increase of ultimate bearing capacity (UBC) approximated at 93%. Similarly, the multi-layered geogrid reinforced sand (N = 0 to 4) increases the UBC by about 75%. The bearing capacity ratio (BCR) of the model footing increases with an increasing load eccentricity to the core boundary of footing; if the load eccentricities increase continuity, the BCR decreases. The tilt of the model footing is increased by increasing the eccentricity and decreases with increasing the number of reinforcing layers.

Description: The article presents parametric analysis regarding the impact of subgrade and backfill stiffness on values and distribution of bending moments in the structural elements of a small integral box bridge made of cast in situ reinforced concrete. The analyzed parameters are the modulus of subgrade reaction under and behind the bridge structure (kv kh). At the beginning, the author presents the integral box bridge and selected parts of the bridge design. In particular, the author focuses on the method of modeling of the subgrade stiffness parameters under and behind the bridge structure, as well as their impact on the values and distribution of bending moments in the bridge structural elements. The bridge was designed by the author and built on the M9 motorway between the towns of Waterford and Kilcullen in Ireland. In conclusions, the author shares his knowledge and experience relating to the design of small integral bridges and culverts and puts forward recommendations as to further research on these type of structures in Poland.

Description: Stone columns (or granular piles, GPs) are progressively being utilized for ground improvement, mostly for pliant edifice such as road mounds, oil depot, and so forth. The present analysis is done by introducing strengthening at both the ends of GP, i.e., bottom and top end so that the bulging problem will be solved and the beneficiary effect of the bearing stratum can be utilized by the bottom strengthening feature. Analysis of a single partially strengthened, at both top and bottom, end-bearing GP is presented in this article in terms of displacement affecting component for the top (DACT) of GP, percentage load transferred to the base (PLTB) of strengthened GP, and normalized shear stress (NSS). The PLTB of the strengthened GP was found to increase considerably. The NSS was found to reduce at the top end of GP and is found to be redistributed along the length of GP.

Description: The paper presents results of a numerical investigation on load capacity of the mixed bench and slab shallow foundations (often used in the process of the modernization of the old, antique buildings, which are suffering from lack of the load capacity). The main trouble with use of existing analytical approaches is a non-unique foundation level of the bench and slab, they could even be founded on different geotechnical layers. Proposed analytical model based on Brinch Hansen (EC-7) approach could deal with such a problem. Results of 2D and 3D numerical modelling (ultimate load of the foundation) are compared to the obtained by using the proposed approach. Influence of the soil above the foundation level is also investigated. Different width to length ratios of the foundation are analyzed (from “short” to “long” foundations). Usability of the proposed analytical model in engineering practice is proved by numerical simulations; the obtained results are on the safe side with quite acceptable margin of additional safety.

Description: The article presents the alternative use of termite mound soils (TMSs) as full replacement for clay soils in brick production. TMSs from two localities, Jawaj and Sene, in Ethiopia were investigated for bricks production. The TMSs samples contained high SiO2 and Al2O3. The TMSs bricks were fired at different temperatures from 500 to 1,000°C. The obtained mean compressive strengths (σ), 18 and 14 MPa, were observed for bricks made from TMSs from Jawaj and Sene, respectively, at the optimum firing temperature of 700°C. The σ of TMSs bricks decreased as the firing temperature increased above 700°C, while for conventional clay soil brick, the σ increased with temperature beyond 700°C. The water absorptions and saturation coefficients of fired TMSs bricks decreased with increased firing temperature. The TMSs bricks meet the standard specification of dimension tolerance only along the height. All the TMSs bricks made from the two localities were not efflorescent. TMSs from Jawaj and Sene sites can be used as a raw material to replace the long-used clay soils for bricks production as a construction material for houses construction in rural and urban areas.

Description: This paper presents experimental research on expanded clay aggregate concrete. The aim of the investigations was to determine if the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. Five concrete series based on the same concrete mix design were made and tested. The degree of pre-wetting of the aggregate was varied: dry aggregate was used in the first series, aggregate with a moisture content of 10% was used in series IA and IB and aggregate with a moisture content of 25% was used in series IIA and IIB. Also the approach to the production process was varied: in series A the water contained in the aggregate was taken into account in the global water-cement ratio (consequently a reduced amount of water was added to the mix), whereas in series B the nominal amount of water was added to the mix (as in the case of dry aggregate). The freeze-thaw resistance criterion was based on the assessment of the decrease of compressive strength and increase in weight loss after exposure to freeze-thaw cycles. The expanded clay aggregate concrete's strength and mass decrements caused by freeze-thaw cycling were used as the measure of its freeze-thaw resistance. The investigations have shown that the pre-wetting of expanded clay aggregate has an effect on the freeze-thaw durability of the expanded clay aggregate concrete. The differences of concrete compressive strength decrease related to freeze-thaw durability may be 2 to 5 times greater when inadequate method of calculating mixing water for concrete is used.

Description: The city of Algiers (Algeria) is a highly seismic area, and therefore, soil liquefaction poses a major concern for structures resting on sandy soil. A campaign of 62 static penetration tests or cone penetrometer tests (CPT) was carried out on a site located in the commune of Dar El Beïda in Algiers. The soil Liquefaction Potential Index (LPI) values were assessed, for each borehole, based on the simplified procedure of Seed and Idriss. On the other hand, the geographic information system and geostatistical analysis were used to quantify the risk of soil liquefaction at the studied site. It is worth mentioning that the (LPI) was taken as a regionalized variable. In addition, the experimental variogram was modeled on the basis of a spherical model. Also, the interpolation of the LPI values in the unsampled locations was performed by the Kriging technique using both isotropic and anisotropic models. Kriging standard deviation maps were produced for both cases. The cross-validation showed that the anisotropic model exhibited a better fit for the interpolation of the values of the soil liquefaction potential. The results obtained indicated that a significant part of the soil is liable to liquefy, in particular in the northwestern region of the study area. The findings suggest that there is a proportional relationship between the risk of liquefaction and the increase or decrease in seismic acceleration.

Description: The purpose of this paper was to present the thermoporoelasticity model adapted for application in modelling processes, where phase transition may occur, such as during underground coal gasification (UCG). The mathematical model of the medium (soil/rock with pores filled with liquid/gas) in non-isothermal conditions is based on Biot's poroelasticity model. The poroelasticity model is expanded here by the influence of temperature and adjusted to the case where both liquid and highly compressible fluid are present in pores by using the gas laws. This requires considering temperature-dependent physical quantities such as pore fluid density, heat transfer coefficient and viscosity as functions of temperature. Based on the proposed mathematical model and the finite element method, a numerical model was built for the purpose of computing processes occurring in the vicinity of the UCG generator. The result of the authors’ work is a three-dimensional (3D) model, which was not only modified, but derived straight from the laws of thermodynamics, where fields of displacement, temperature and fluid flow are coupled. The model makes it possible to determine results significant to modelling of the UCG process, the reach of the gaseous phase's presence in pores, subsidence values, temperature distribution and directions and rate of seepage, without losing the simplicity and elegance of Biot's original concept. Next, the results of simulations for a hypothetical deposit to estimate the environmental impact of UCG are presented. After applying specific geometry and parameters, the model can be useful for verifying if the chosen technology of UCG in specific conditions will be safe for the environment and infrastructure.

Description: It is well-known that the longwall mining method (with roof caving) is widely used in underground mining extraction for bedded deposits (e.g. coal) due to its numerous advantages. Generally, this method is not commonly applied for ore deposits such as copper deposit. In Poland, the longwall mining method has been tested for thin copper deposits at the Polkowice-Sieroszowice copper mine (KGHM). Various failure modes were observed during longwall operation in the 5A/1 panel. This paper aims to examine these occurred failures. To do so, an analysis has been conducted using 3D numerical modelling to investigate the failure mode and mechanism. Based on the 3D numerical modelling results with extensive in situ measurements, causes of failure are determined and practical recommendations for further copper longwall operations are presented.

Description: Sandstone is one of the most popular building materials since the earliest times. It has various textures and colours as well as good technical parameters. Sandstones, having such wide applications, are subjected to various external factors during the period of use. So, it is of utmost importance to have a good knowledge of their strength parameters. We employed a numerical method called Discrete Element Method to examine in a non-invasive manner the mechanical strength of industrial sandstones, that are commonly used as broken stones in road construction, cladding material, paving stones, pavement tiles and so on. Various mechanical external factors were considered, such as breaking, compressional and abrasion forces or impact by external objects and vibrations. Fragmentation of the considered sandstones under compressional regime was a source of knowledge about energy storage inside the material and energy release, as well as appearance of fractures inside the matter and final sandstone fragmentation into crumbs.

Description: With the rapidly developing road transport, there is a demand for new roads to be constructed and for the existing ones to be repaired or extended. The base of any road is its foundation, usually made of crushed or uncrushed aggregate. To be used for road foundation purposes, a material needs to meet many requirements, as imposed by relevant standards. One of the basic tests to assess the suitability of an aggregate is to determine its California bearing ratio (CBR). This paper presents the results of CBR tests for mixed aggregate with the grading of 0–31.5 and 0–63 mm. Detailed assessments were carried out for penetration curves, which in many cases need to be adjusted to meet industry standards. The adjustment of plunger penetration curves in aggregate samples causes CBR to increase compared to the original curves.

Description: Stability checking is an essential element of the dimensioning of steel frame structures. One of the stability checking methods allowed by EN 1993-1-1 is the so-called general method of assessing structural stability, based on buckling curves and relative structure slenderness λ ¯ op { ar lambda _{op}} usually determined through numerical analyses. But this method is not widely used because of the limited computing capabilities of the engineering programs dedicated to static load analyses and difficulties in interpreting the results of the computations. The commonly used computer programs enable one to determine the shape of buckling and critical load amplifier αcr , from which one cannot directly determine the risk of buckling of a real structure. This paper presents a modified and innovative approach to the general method of assessing structural stability, which uses only three parameters, that is, the type of cross section, cross-section strength utilisation and αcr , to determine a member’s/structure’s bearing capacity mobilisation from the stability condition. The problem solution is presented in the form of simple formulas and legible diagrams. Finally, synthetic conclusions are formulated.

Description: Two models of vibrations of the Euler–Bernoulli beam under a moving force, based on two different versions of the nonlocal gradient theory of elasticity, namely, the Eringen model, in which the strain is a function of stress gradient, and the nonlocal model, in which the stress is a function of strains gradient, were studied and compared. A dynamic response of a finite, simply supported beam under a moving force was evaluated. The force is moving along the beam with a constant velocity. Particular solutions in the form of an infinite series and some solutions in a closed form as well as the numerical results were presented.

Description: The method of unconventional solid rock loosening with undercutting anchors and the literature analysis of the problem are presented. The tests and test results of the rocks loosening process with a fixed undercutting anchor are described. The tests were carried out within the RODEST project, OPUS 10 competition No. 2015/19/B/ST10/02817, financed by the National Science Centre. Numerical modeling process as well as a series of laboratory and in situ tests were carried out. The test stand equipment and methodology for the in situ tests are presented. The tests were conducted in four mines, which allowed to obtain and determine the following characteristics: loosening force as a function of anchoring depth (for a given type of rock),the range of rock loosening in a function of anchoring depth (for a given type of rock), andloosened rock volume as a function of anchoring depth (for a given type of rock).The in situ test results are compared with the concrete capacity design (CCD) model used for the calculation of anchor load capacity in concrete.

Description: The design of shallow foundations on swelling soils needs a thorough study to evaluate the effect of swelling potential soil on the final foundation heave. For this reason, a simple analytical approach based on the soil stress state under the foundation can be used to calculate the foundation heave. This paper reports a set of analytical and numerical analysis using the finite-difference code (FLAC 3D), performed on an isolated shallow foundation founded on a swelling soil mass at N’Gaous city in Batna Province, Algeria, subjected to distributed vertical loads. Further, the influence of some parameters on total heave was analyzed, such as the embedded foundation and soil stiffness. The analysis results from the proposed 3D modelling was compared and discussed with analytical results. The numerical results obtained show a good agreement with the analytical solutions based on oedometer tests proposed in the literature, and deliver a satisfactory prediction of the heave of the shallow foundations.

Description: The objective of this paper is to describe the effect of cavities on the bearing capacity of two interfering footings based on granular soil using an exclusively experimental approach with a test model designed in the laboratory. The experimental protocol was carried out based on the variation of several parameters such as the spacing (x) (axis to axis) between the footings, and the distance (H) between the footings and cavities and between the cavities axes (L). The results highlight the effect of cavities and the interference of two strip footings on the bearing capacity factor (q) and efficiency factor (EF). Moreover, the results revealed that, in the case wherein the distance between the footings and the cavity is greater than 3, the cavity impact is eliminated.

Description: The present study shows the results of a 2D local seismic response (LSR) analysis, simulated for a geomechanical model consisting of a layered carbonate rock mass with hypogean karst caves and a structural–lithostratigraphic complex setting, in an area within the Municipality of Turi (Apulia, Italy). In this case study a Distinct Element Code (DEM) code (UDEC) was used for the LSR simulations conducted on a model both in the absence and in the presence of two overlapping karst caves. The preliminary stress–strain model analysis show some tensile yielding points clustered on the roof of the upper karst cave, already in static conditions, and the phenomenon becomes even more noticeable in dynamic conditions. This is perfectly in agreement with the real occurrence of a sinkhole that brought to the light the underlying karst cave, in the case study area, in the recent past.The amplification/deamplification factor (FA) was calculated as the ratio of the top value to the bottom value in the model, both of the max X-acceleration and of the spectral Fourier amplitude in three different ranges of frequencies, in order to estimate the effects of LSR on the X-component of the seismic input. According to the previous studies, the results obtained show a generalised deamplification of the seismic ground motion at the top of the model, both without and with underground karst caves, caused by the presence of the upper karst cave and by the seismic energy absorption because of layers’ discontinuity.

Description: This paper focuses on the setup of axial bearing capacity of open ended tubular steel piles that are used for offshore foundation systems such as those of wind turbines. A comparative evaluation of the most commonly used models for setup prediction shows an upper estimate bound and a lower estimate bound, which correspond approximately to a setup rate of 60% increase per log cycle of time and 20% increase per log cycle of time, respectively. This finding is validated with the results of case histories reported in literature, which show that the setup values of most case histories considered lie in the best estimate zone between the upper estimate zone and the lower estimate zone. The analysis results show a minimum setup factor of approximately 1.5 for 100 days following end of driving of open-ended tubular steel pile driven in sand.

Description: Dynamic tests are one of the most significant diagnostic procedures applied in Bridge Health Monitoring in many countries. The paper presents a proposal of unified classification of the bridge dynamic tests together with review of the testing methods, including tests under designed and controlled loads, arranged short-term tests under normal traffic loads as well as permanent dynamic monitoring by means of built-in gauges mounted on a structure. Classification of bridge dynamic tests is proposed taking into account various types of vibration excitation methods, measured parameters and possible applications of obtained results in the Bridge Health Monitoring. General rules and procedures of bridge dynamic tests are described and discussed.

Description: This article presents a modified incremental model describing pre-failure deformations of granular soils under classical triaxial conditions. The original shape of equations has been proposed by Sawicki and Świdziński [40, 41]. A new form of equations that are consistent with the proposed definitions of deviatoric loading and unloading is suggested. Triaxial tests necessary for calibrating the proposed model have been performed. The modified model is used to simulate the deformations and stability of sand for every pre-failure loading path and makes it possible to describe the behaviour of granular soil under both drained and undrained conditions.A comparison of experimental and numerical results is presented. All investigations were performed in a classical tri-axial apparatus.

Description: This article presents the methodology and results of single shear tests of bolt rods under dynamic impact loading generated by means of a drop hammer. Comparative analysis was also performed for bolt rod load capacity, stress and shear work under static and dynamic (impact) loading. The developed method of single shear testing of bolt rods under impact loading makes it possible to obtain repeatable test results concerning maximum bolt rod shearing force, shear stress and shear work values.Comparative shear tests of four types of bolt rods under static and impact loading showed that the APB-type bolt rods made of AP770 steel, which was characterised by having the highest strength, exhibited the greatest shear work. AM22-type bolt rods exhibited a very similar work value. Though the AM22-type bolt rods made of A500sh steel demonstrated lower strength than the APB-type bolts, as well as a smaller diameter and cross section, they dissipated the impact energy better thanks to their higher plasticity. This could indicate the direction of optimisation for bolt rods in order to increase their impact strength.Mathematical relationships were also formulated for selected tests, describing the real single shear courses F d =f(t) of bolts under impact loading. The obtained relationships could be applied in the load assessment process of bolt rods intended for use under roof caving, tremor and rock burst conditions.

Description: The results of studies of the crushing process in a double toggle jaw crusher are presented. This process was carried out on six sets of crushing plates. The first three of them are used in industrial crushers – plates with a flat working surface and a triangular profile (in this work, under consideration were profiles with teeth angle γ = 90°). The fourth and fifth type refer to plates with a variable pitch t and teeth height with a triangular shape of the teeth. In the sixth solution, plates with variable pitch and width of the wedged teeth are proposed.The results of the basic process parameters are shown, that is, average degree of fineness n, technical performance Wt, crushing energy L and crushing force F, sieve analysis of crushing product. The obtained results are the basis for the assessment of the suitability of various types of plates, especially plates with a new profile, which have an altered shape in comparison with the plates used in crushers so far.The crushing tests were carried out with the same dimension of outlet slot er = 24 mm, close to the pitch size for plates with triangular profile. Tests were performed on the “Mucharz” sandstone. Samples from a series of blocks of different size and geometric shape were prepared. This work also presents feed mass influence on crushing process efficiency.The plates with variable pitch and width of teeth are beneficial because of lower crushing force and energy.

Description: Wellbore collapse is an instability-event that occurs at low mud density and leads to unfavorable economic project, reaching billions of US dollars. Thus, it is important to accurately determine its value, especially in deepwater horizontal wellbores. The main reasons for nontrivial problems with such wellbores are evident: the shale encountered are anisotropic in nature and possess planes of weakness; they react with water-based mud, generate osmotic stresses, swell, and fall unto the wellbore bottom, thereby increasing the non-productive time. To this end, salts are added to reduce the collapse tendency, but it is not currently known what amount of salt addition maintains stability, and does not lead to wellbore fracture; in deepwater, the current trend in global warming means there is a future concern to the industry. As the climate temperature increases, more ice melts from the polar region, the seawater expands and the sea level rises. How to incorporate the corresponding effect on collapse gradient is scarcely known. This study captures the major concerns stated above into wellbore stability analysis. Following the classical approach for geomechanical analysis, Mogi-Coulomb criterion was combined with a constitutive stress equation comprising contributions from mechanical and osmotic potentials of mud and shale. A sophisticated industry model was used to consider the deepwater effect. The results show significant reduction in collapse gradient as the water depth increases, also, larger difference between the mud and shale chemical activities represents higher complexities in the wellbore. In addition, the reduction in the chemical activities of mud limited to 37.5% of the initial value can be practically safe.

Description: Increasingly high demands on environmental protection are intensifying the development of sustainable construction. Ventilated facades can provide an energy-efficient alternative to standard facades, that is, external thermal insulation composite systems (ETICS). The article compares standard facades, which was a reference, to ventilated facades in two variants: closed joints and open joints. The comparison was made by means of numerical simulations of computational fluid dynamic (CFD), under conditions of high outside temperature and high sunshine. The results showed great benefits of using ventilated facades in such external climate conditions. It was also observed that the selection of the variant of ventilated facade in the system of close or open joints has minimal influence on thermal efficiency of the whole partition.

Description: This article presents the results of experimental work carried out both in situ (coring; pressuremeter test) and in the laboratory (drying-wetting and oedometric tests) to describe the volumetric behavior on drying-wetting path of a swelling clayey soil of eastern Algeria. In order to perform drying-wetting tests the osmotic technique and saturated salts solutions were used. These suction-imposed methods have gained widespread acceptance as reliable methods for imposing suction on soil specimens. They allowed to sweep a wide range of suctions between 0 and 500 MPa. The ability to impose suction on soil specimens allows for drying and wetting stress paths to be applied to evaluate resulting changes in state parameters (void ratio, degree of saturation and water content). These paths were carried out on specimens with different initial states. Slurries of soil were used to characterize the reference behavior, while the undisturbed soil samples allow to describe the behavior of material under in situ conditions. In the last part of this article and to specify the behavior observed in the saturated domain, a comparison between the resulting deformations of the drying-wetting test and those resulting from the oedometric test was made.

Description: The algorithm presented in this paper is intended for the analysis of deformations of shells in the construction phase of soil-shell objects when strain gauges and geodetic measurements are used. During the construction of such an object, large displacement values occur and the impact of axial forces on the displacement of a corrugated metal sheet is small. Internal forces (strain gauges), as well as the displacements of a selected circumferential band of the shell are determined directly from such observations.The paper presents two examples of the analysis of large span shell structures of constructed objects, as well as the assessment of the effectiveness of the finite difference method (FDM) in beam schemes. Good deformation mapping was indicated using the collocation algorithm and the differential approach to the solution when there is a dense mesh and regular distribution of measuring points. In the analysed examples, a significant divergence between the support conditions adopted in the FEM calculation models and the actual static conditions in the objects was indicated. The collocation algorithm is especially designed for such situations. Collocation points in such a solution are used to consider a beam – separated from a structure and without boundary constraints, but with specific changes in curvature – as a reference system, which is determined from the geodetic measurements of two collocation points.

Description: The article addresses the application of non-classical operational calculus to approximative solutions of engineering problems. The engineering-sound examples show that a continuous–discrete problem transformation from differential unequivocal problem to a differential wildcard problem, triggering a change in solution quality. A number of approximative methods are capable to alter both quantitative and qualitative solution effects.

Description: In a piled-raft foundation, the interaction between structural elements and soil continuum can be simulated very precisely by numerical modeling. In the present study, 3D finite element model has been used to examine the settlement, load-sharing, bending moment, and shear force behavior of piled-raft foundation on different soil profiles for different load configurations and pile-raft configurations (PRCs). The model incorporates the pile-to-soil and raft-to-soil interactions by means of interface elements. The effect of parameters such as pile spacing and raft thickness are also studied. For any soil profile, larger pile spacing is observed to be more efficient in reducing the average settlement and enhancing the load-sharing coefficient. The smaller pile spacing is observed to be efficient in reducing the differential settlement. For any soil profile, the behavior of piled-raft foundation is significantly affected by the PRCs and load configurations. Furthermore, the raft thickness has significant effect on settlement, bending moment, and shears force. Thus, the results of the present study can be used as guidelines for analyzing and designing large piled-raft foundation.

Description: The problem of numerical simulation of the material interface response under monotonic and cyclic loading is of fundamental scientific and engineering importance. In fact, such interfaces occur in most engineering and geotechnical structures. The present work is devoted to the deformational response analysis of contact interfaces under monotonic and cyclic loads. The class of materials includes rock and structural joints, soil structure interfaces, masonry and cementitious joints, localized shear bands and so on.The aim of the proposed model is to simulate the cyclic shear test under constant normal load. The associated dilatancy effect is associated with the configurational effects of asperity interaction or dilatancy of wear debris layer. The large primary asperities are assumed as responsible for interfacial dilation and small size asperities as governing frictional sliding and hysteresis response. The elliptic loading yield function is assumed to translate and rotate during progressive or reverse loading events. The model formulation is discussed and confronted with experimental data.

Description: The paper presents the results of laboratory tests of plastic limit wP and liquid limit wL of Eemian gyttja characterized by different organic matter content Iom and calcium carbonate content CaCO3. Comparison of the liquid limit wL determined with the use of the Casagrande apparatus wLC and a cone penetrometer with cones having apex angles of 60° wL60 and 30° wL30 is shown. Based on statistical analysis of the test results, single- and two-factor empirical relationships for evaluating the plastic limit wP and liquid limit wL of Eemian gyttja depending on the organic matter content Iom and/or calcium carbonate content CaCO3 are presented in this study.

Description: In coastal regions, earthquakes caused severe damage to marine structures. Many researchers have conducted numerical investigations in order to understand the dynamic behavior of these structures. The most frequently used model in numerical calculations of soil is the linear-elastic perfectly plastic model with a Mohr-Coulomb failure criterion (MC model). It is recommended to use this model to represent a first-order approximation of soil behavior. Therefore, it is necessary to accommodate soil constitutive models for the specific geotechnical problems.In this paper, three soil constitutive models with different accuracy were applied by using the two-dimensional finite element software PLAXIS to study the behavior of pile-supported wharf embedded in rock dike, under the 1989 Loma Prieta earthquake. These models are: a linear-elastic perfectly plastic model (MC model), an elastoplastic model with isotropic hardening (HS model), and the Hardening Soil model with an extension to the small-strain stiffness (HSS model).A typical pile-supported wharf structure with batter piles from the western United States ports was selected to perform the study. The wharf included cut-slope (sliver) rock dike configuration, which is constituted by a thin layer of rockfill overlaid by a slope of loose sand. The foundation soil and the backfill soil behind the wharf were all dense sand. The soil parameters used in the study were calibrated in numerical soil element tests (Oedometer and Triaxial tests).The wharf displacement and pore pressure results obtained using models with different accuracy were compared to the numerical results of Heidary-Torkamani et al.[28] It was found that the Hardening Soil model with small-strain stiffness (HSS model) gives clearly better results than the MC and HS models.Afterwards, the pile displacements in sloping rockfill were analyzed. The displacement time histories of the rock dike at the top and at the toe were also exposed. It can be noted that during the earthquake there was a significant lateral ground displacement at the upper part of the embankment due to the liquefaction of loose sand. This movement caused displacement at the dike top greater than its displacement at the toe. Consequently, the behavior of the wharf was affected and the pile displacements were important, specially the piles closest to the dike top.

Description: The paper discusses existing models used to estimate the thermal conductivity of the soil medium. The considerations are divided into three general sections. In the first section of the paper, we focus on the presentation of empirical models. Here, in the case of Johansen method, different relations for Kersten number are also presented. In the next part, theoretical models are considered. In the following part, selected models were used to predict measured thermal conductivities of coarse- and fine-grained soils, at different water contents. Based on these predictions as well as on the authors’ experience, a critical assessment of the existing models is provided. The remarks as well as advantages and disadvantages of those models are summarized in a tabular form. The latter is important from a practical point of view; based on the table content, one can simply choose a model that is suitable for the particular problem.

Description: In this study, firstly, the behavior of a high steel frame equipped with tuned mass damper (TMD) due to several seismic records is investigated considering the structural and seismic uncertainties. Then, machine learning methods including artificial neural networks (ANN), decision tree (DT), Naïve Bayes (NB) and support vector machines (SVM) are used to predict the behavior of the structure. Results showed that among the machine learning models, SVM with Gaussian kernel has better performance since it is capable of predicting the drift of stories and the failure probability with R2 value equal to 0.99. Furthermore, results of feature selection algorithms revealed that when using TMD in high steel structures, seismic uncertainties have greater influences on drift of stories in comparison with structural uncertainties. Findings of this study can be used in design and probabilistic analysis of high steel frames equipped with TMDs.

Description: This paper presents an efficient method and its usage for the three-dimensional random bearing capacity evaluation for square and rectangular footings. One of the objectives of the study is to deliver graphs that can be used to easily estimate the approximated values of coefficients of variations of undrained bearing capacity. The numerical calculations were based on the proposed method that connects three-dimensional failure mechanism, simulated annealing optimization scheme and spatial averaging. The random field is used for describing the spatial variability of undrained shear strength. The proposed approach is in accordance with a constant covariance matrix concept, that results in a highly efficient tool for estimating the probabilistic characteristics of bearing capacity. As a result, numerous three-dimensional simulations were performed to create the graphs. The considered covariance matrix is a result of Vanmarcke’s spatial averaging discretization of a random field in the dissipation regions to the single random variables. The matrix describes mutual correlation between each dissipation region (or between those random variables). However, in the presented approach, the matrix was obtained for the expected value of undrained shear strength and keep constant during Monte Carlo simulations. The graphs were established in dimensionless coordinates that vary in the observable in practice ranges of parameters (i.e., values of fluctuation scales, foundation sizes and shapes). Examples of usage were given in the study to illustrate the application possibility of the graphs. Moreover, the comparison with the approach that uses individually determined covariance matrix is shown.

Description: In this article, the computational methodology of the catenary–train–track system vibration analysis is presented and used to estimate the influence of vehicle body vibrations on the pantograph–catenary dynamic interaction. This issue is rarely referred in the literature, although any perturbations appearing at the pantograph–catenary interface are of great importance for high-speed railways. Vehicle body vibrations considered in this article are induced by the passage of train through the track stiffness discontinuity, being a frequent cause of significant dynamic effects. First, the most important assumptions of the computational model are presented, including the general idea of decomposing catenary–train–track dynamic system into two main subsystems and the concept of one-way coupling between them. Then, the pantograph base vibrations calculated for two train speeds (60 m/s, 100 m/s) and two cases of track discontinuity (a sudden increase and a sudden decrease in the stiffness of track substrate) are analyzed. Two cases of the railway vehicle suspension are considered – a typical two-stage suspension and a primary suspension alone. To evaluate catenary–pantograph dynamic interaction, the dynamic uplift of the contact wire at steady arm and the pantograph contact force is computed. It is demonstrated that an efficiency of the two-stage suspension grows with the train speed; hence, such vehicle suspension effectively suppresses strong sudden shocks of vehicle body, appearing while the train passes through the track stiffness discontinuity at a high speed. In a hypothetical case when the one-stage vehicle suspension is used, the pantograph base vibrations may increase the number of contact loss events at the catenary–pantograph interface.

Description: Time dependence of soft soils has already been thoroughly investigated. The knowledge on creep and relaxation phenomena is generally available in the literature. However, it is still rarely applied in practice. Regarding the organic soils, geotechnical engineers mostly base their calculations on the simple assumptions. Yet, as presented within this article, the rate-dependent behaviour of soft soils is a very special and important feature. It influences both the strength and the stiffness of a soil depending on time. It is, thus, significant to account for time dependence in the geotechnical design when considering the soft soils. This can result in a more robust and economic design of geotechnical structures. Hence, the up-to-date possibilities of regarding creep in practice, which are provided by the existing theories, are reviewed herein.In this article, we first justify the importance of creep effects in practical applications. Next, we present the fundamental theories explaining the time-dependent behaviour of organic soils. Finally, the revision of the existing constitutive models that can be used in numerical simulations involving soft soils is introduced. Both the models that are implemented in the commercial geotechnical software and some more advanced models that take into account further aspects of soft soils behaviour are revised. The assumptions, the basic equations along with the advantages and the drawbacks of the considered models are described.

Description: Water infiltration through coal stocks exposed to weather elements represents a key issue for many old mining sites and coal-fired power plants from the environmental point of view, considering the negative impact on human health of the deriving groundwater, soil and air pollution. Within this context, the paper investigates the hydraulic behaviour of a self-weight compacted unsaturated coal mass and its impact on the numerical prediction of infiltration induced by rainfall events. In particular, the work focuses on the experimental investigation carried out at different representative scales, from the grain scale to physical modelling. The material, when starting from uncompacted conditions, seems to be characterized by metastable structure, which tends to collapse under imbibition. In addition, direct numerical predictions of the seepage regime through a partially saturated coal mass have been performed. As the compaction of the coal stock induced by dozers has not been taken into account, the numerical simulations represent a conservative approach for the assessment of chemical pollution hazard associated to water infiltration into a real stockpile under operational conditions.

Description: This paper presents a laboratory study of the combined effect of the water content and fines content on the mechanical behaviour of Chlef sand in a medium dense state (RD = 65%) and dense state (RD = 80%). Several mechanical parameters were evaluated such as shear strength, cohesion and friction angle at different water content w = 0, 1, 2 and 3% and different fines content Fc = 0, 10, 20, 30 and 40%. The test results showed that the shear strength of Chlef sand decrease with the increase fines content Fc = 0 to 40%, our tests result also showed that the water content has a significant influence on the shear strength which decreases with the increase in the water content w = 0 to 3%. The fines content and the water content have a significant influence on the mechanical parameters c and φ. Cohesion increases with the percentage of fines and decreases with the increase of the water content while the friction angle decreases with the increase the fines content and the water content.

Description: The constantly growing, broadly understood, construction industry requires the use of a large amount of aggregates. The construction of roads, motorways, railway lines and hydrotechnical structures requires the use of aggregates of high quality, which is primarily determined by mechanical properties. The basic parameters describing mechanical properties of aggregates are the Los Angeles (LA) fragmentation resistance coefficient and the Micro-Deval (MDE) abrasion resistance coefficient. The LA and MDE coefficients depend mainly on the type of rock and its physical and mechanical properties. This has been thoroughly researched and documented as evidenced by the abundant literature in the field. However, the correlation between LA and MDE coefficients still gives rise to extensive discussions and some concerns. A number of publications demonstrate dependencies for various types of aggregates. Therefore, research was undertaken to present statistical analysis for one type of aggregate and one geological area.This article presents the results of the fragmentation resistance test in the Los Angeles drum and the abrasion resistance test in the Micro-Deval drum of aggregates from Carpathian sandstone deposits. Aggregate samples were divided into three groups according to the location of the deposits and the tectonic unit from which they originated. The obtained results were subjected to static analysis to fit the best mathematical function describing the relationship between the two parameters.

Description: This paper identifies the threats and risks of a terrorist attack on a critical infrastructure facility based on the example of Żelazny Most Tailings Storage Facility (OUOW). The threat analysis primarily took into account the threats of deliberate human actions. Identification of potential threats concerning the infrastructure surrounding the facility was conducted based on information that is readily available on the Internet. The reasons why it may be a potential target were also justified. Numerical calculations of the stress–deformation scale of the initial state of the reservoir, based on the Biot model with the Kelvin–Voight rheological skeleton, were presented as a starting point for in-depth research on the scale of threats and risks to the reservoir. The presented numerical model can be a starting point for calculating the stability of a reservoir subjected to explosives. The facility constitutes a major element of Lubińsko-Głogowski Okręg Miedziowy (Lubin-Głogów Copper District). OUOW Żelazny Most is the biggest such facility in Europe and is utilized to collect tailing waist. When expanded in its southern quarter, the facility will be the biggest in the world.

Description: Geogrids are widely used in civil engineering projects to reinforce road and railway structures. This paper presents research on the shearing strength of soil samples that have been reinforced with geogrids. The relationship between soil and geogrids is explored and evaluated by modeling the mechanical behavior of heterogeneous materials. For the purposes of this research, data obtained from tests of unreinforced sand samples with triaxial cells were compared with the data obtained from tests of reinforced sand samples. It was found that the shearing strength for reinforced samples was higher (from 9% to 49%) compared to unreinforced samples. Some damage to the geogrid was detected during the experiment, and for this reason, the same tests were numerically simulated for both unreinforced samples and samples reinforced with geogrids. Numerical simulations revealed the main reasons for damage to the geogrids during triaxial testing.

Description: This article concerns the assessment of selected physical and mechanical properties of a dump soil. The dump soil is a specific soil with a very heterogeneous internal structure. Next to each other, there may be lumps and crumbs of cohesive soils mixed with non-cohesive soils accompanied by a very diverse admixture of organic substance. In addition, the soil in the waste dump, in spatial terms, may significantly differ in consistency and density. This is the result of the process of forming a dump soil, which takes place in three stages: excavation, transport and dumping. A heterogeneous soil deposited within the waste dump is subject to further processes: consolidation, compaction and creeping. Changes occurring in the course of these processes have a significant impact on the development of the properties of the dump soil.Due to the large diversity of the tested soils, the results of their properties were divided into two groups, based on type and consistency of soil. This allows us to estimate the selected properties of the dump soil only on the basis of their macroscopic analysis.

Description: The issue of the stratification of the underground subsoil is one of the principal geotechnical challenges. The development of the Cone Penetration Tests (CPTu) has resulted in the possibility to record parameters in a quasi-continuous way, which provides a very detailed description of the soil response. Such accurate measurements may therefore be treated as a signal or image and be analysed as such. This paper presents the application of high-pass spatial filters to perform soil stratification on the basis of the static penetration test. The presented algorithm has been tested on the test data set provided by the Organizers of TC304 Student Contest on Spatial Data Analysis (September 22, 2019, Hannover, Germany). It provides reasonable results at negligible computational cost and is applicable to most soils, especially if the contrast between the parameters of the adjacent layers is significant.

Description: The use of waste materials in civil engineering applications has gained importance nowadays. Consuming limited natural resources and increasing waste disposal costs have led researchers to evaluate waste materials for different geotechnical applications. In this respect, some waste materials are used as reinforcement in soils to improve their engineering properties. The main objective of this paper was to investigate the usability of waste polypropylene fiber as a reinforcement material in high plasticity fine-grained soils. For this purpose, waste toothbrush bristle (WTB) was used as a polypropylene fiber reinforcement material and added to fine-grained soil at ratios of 0.2%, 0.4%, 0.6% and 0.8% by dry total weight. The effect of WTB on freezing–thawing behavior and unconfined compression strength of unreinforced and reinforced clayey soil was evaluated. The results indicated that addition of WTB to high plasticity clay improved its behavior against freezing–thawing. Also, undrained shear strength increases with respect to increment in WTB ratio.

Description: The aim of this study is to consider the effects of the variation of shear modulus ratio (G/G0) and damping ratio (ξ) of soil, obtained by a linear iterative method based on the design spectra of seismic codes, the soil environment in terms of uncertainties in shear modulus using Monte Carlo simulations and the foundation damping (ξf) of flexible base for analyses of the Soil-Structure Interaction (SSI) problems. A squat structure with circular shallow foundation resting on a soil layer over a homogeneous half-space is studied by using cone model and considering seismic zone effect on structural response. Firstly, after showing the effects of the correction of G and ξ on impedance functions and the responses of soil-foundation-structure system, a study is carried out to compare these effects to those of the modelling of uncertainties in shear modulus as random variations. Secondly, a comparative analysis on design response spectra and base shear forces was carried out for four seismic codes (Algerian Seismic Rules RPA99-2003, Eurocode 8–2004, International Building Code IBC-2015 and Indian Code IS-1893-2002) considering the three cases of SSI: SSI effects (initial G and ξ), nonlinear SSI (corrected G and ξ) and stochastic SSI (random G with COV = 20%) compared to the fixed base case. Results show that the correction of G and ξ, according to the equivalent nonlinear method in all the cases, leads to a remarkable decrease in peak responses but show a huge amount of reduction in the second study for IBC-2015 and IS-1893-2002 codes compared to the other codes.

Description: This paper presents a methodology based on the finite element method to simulate the flow of granular materials. Moreover, it allows proper estimation of dynamic pressure during silo discharge since this subject is still under discussion, especially for designing silos with an insert (an input element). A 2-D simulation of the discharge process of a cylindrical silo with cone and a central discharging orifice was performed. Two cases were studied, with and without using insert in silo. Numerical analysis was carried out with the help of the uncoupled arbitrary Lagrangian–Eulerian (ALE) approach. The resulting dynamic pressure distribution on the silo wall for each of the two cases was inferred numerically. The resulting values of pressure were compared with the results of the experimental study on a cylindrical metal silo to demonstrate the accuracy of the numerical model in determining the dynamic wall pressure, especially in the case of using an insert in silo during discharge.

Description: The article presents a method of calibration of material parameters of a numerical model based on a genetic algorithm, which allows to match the calculation results with measurements from the geotechnical monitoring network. This method can be used for the maintenance of objects managed by the observation method, which requires continuous monitoring and design alterations. The correctness of the calibration method has been verified on the basis of artificially generated data in order to eliminate inaccuracies related to approximations resulting from the numerical model generation. Using the example of the tailing dam model the quality of prediction of the selected measurement points was verified. Moreover, changes of factor of safety values, which is an important indicator for designing this type of construction, were analyzed. It was decided to exploit the case of dam of reservoir, which is under continuous construction, that is dam height is increasing constantly, because in this situation the use of the observation method is relevant.

Description: This paper deals with elementary geotechnical tests: triaxial and direct shear of cohesionless sand using the discrete element method (DEM). The capabilities of the numerical DEM code are shown, with a special focus on the early phenomena appearance in localization zones. The numerical tests were performed in 3D conditions with spherical grains. Contact moments law was introduced due to simulate not perfectly round sand grains. The influence of different physical parameters was studied, e.g. initial density or confining pressure. The sieve curve corresponded to the Karlsruhe sand [1]; however, in some tests, it was linearly scaled. Special attention was laid on the behaviour of the sand grains inside localization, e.g. rotation, porosity, fluctuations, etc. and forces redistribution. Emphasis was given on the pre-failure regime and early localization predictors.

Description: The article presents problem of non-uniform foundation of structures in weak wet subsoil. The problem is illustrated with the case study of two-chamber-reinforced concrete water tank constructed in 1920s of 20th century, which cracked during construction. Under part of foundation, where the peat was found, the concrete piles were introduced.The results of five-year measurement of crack widths with crack gauges and geodesic measurements of vertical displacement of tank were presented. These results indicate that the tank is not stable and part of broken tank supported on piles is movable.On the basis of the presented data, the general conclusions concerning the non-uniform founding of tanks are formulated.

Description: The inclusions of geosynthetic materials (fibers, geomembranes and geotextiles) is a new improvement technique that ensures uniformity in the soil during construction. The use of tension resisting discreet inclusions like polypropylene fibers has attracted a significant amount of attention these past years in the improvement of soil performance in a cost-efficient manner. A series of direct shear box tests were conducted on unreinforced and reinforced Chlef sand with different contents of fibers (0, 0.25, 0.5 and0.75%) in order to study the mechanical behavior of sand reinforced with polypropylene fibers. Samples were prepared at three different relative densities 30%, 50% and 80% representing loose, medium dense and dense states,respectively, and performed at normal stresses of 50, 100 and 200 kPa. The experimental results show that the mechanical characteristics are improved with the addition of polypropylene fibers. The inclusion of randomly distributed fibers has a significant effect on the shear strength and dilation of sandy soil. The increase in strength is a function of fiber content, where it has been shown that the mechanical characteristics improve with the increase in fiber content up to 0.75%, this improvement is more significant at a higher normal stress and relative density.

Description: The present article examines the problem related to the axisymmetric torsion of an elastic layer by a circular rigid disc at the symmetry plane. The layer is sandwiched between two similar elastic half-spaces with two penny-shaped cracks symmetrically located at the interfaces between the two bonded dissimilar media. The mixed boundary-value problem is transformed, by means of the Hankel integral transformation, to dual integral equations, that are reduced, to a Fredholm integral equation of the second kind. The numerical methods are used to convert the resulting system to a system of infinite algebraic equations. Some physical quantities such as the stress intensity factor and the moment are calculated and presented numerically according to some relevant parameters. The numerical results show that the discontinuities around the crack and the inclusion cause a large increase in the stresses that decay with distance from the disc-loaded. Furthermore, the dependence of the stress intensity factor on the disc size, the distance between the crack and the disc, and the shear parameter is also observerd.

Description: A characteristic feature of soil-steel structures is that, unlike in typical bridges, the backfill and the carriageway pavement with its foundation play a major role in bearing loads. In the soil-steel structure model, one can distinguish two structural subsystems: the shell made of corrugated plates and the backfill with the pavement layers. The interactions between the subsystems are modelled as interfacial interactions, that is, forces normal and tangent to the surface of the shell. This is a static condition of the consistency of mutual interactions between the surrounding earth and the shell, considering that slip can arise at the interface between the subsystems. This paper presents an algorithm for determining the internal forces in the shell on the basis of the unit strains in the corrugated plates, and subsequently, the interfacial interactions. The effects of loads arising during the construction of a soil-steel bridge when, for example, construction machines drive over the structure, are taken into account in the analysis of the internal forces in the shell and in the surrounding earth. During construction, the forces in the shell are usually many times greater than the ones generated by service loads. Thus, the analytical results presented in this paper provide the basis for predicting the behaviour of the soil medium under operational loads.

Description: This article presents the results of laboratory tests on soft, normally consolidated soils from the Vistula Marshlands. Samples of high-plasticity organic soils (muds) taken from 3.2–4.0 m and 9.5–10.0 m depth, as well as peat deposit at 14.0 m, are analysed. Presented case study confirms the applicability of the Norwegian Institute of Technology (NTH) method based on Cone Penetration Tests (CPTU) and allows for a conservative estimation of effective friction angle for muds. The plastification angle equal to 14.5° for organic silt, applied in the modified NTH method, fits well the triaxial test (TX) results. Moreover, the dilative-contractive behaviour according to the CPTU soil classification based on the Robertson’s proposal from 2016 corresponds well with volumetric changes observed in the consolidated drained triaxial compression tests. The internal friction angles of the Vistula Marshlands’ muds and peats are lower in comparison with the database of similar soft soils.

Description: Based on the response of small-scale model square footing, the present paper shows the results of an experimental bearing capacity of eccentrically loaded square footing, near a slope sand bed. To reach this aim, a steel model square footing of (150 mm × 150 mm) and a varied sand relative density of 30%, 50% and 70% are used. The bearing capacity-settlement relationship of footing located at the edge of a slope and the effect of various parameters such as eccentricity (e) and dimensions report (b/B) were studied. Test results indicate that ultimate bearing capacity decreases with increasing load eccentricity to the core boundary of footing and that as far as the footing is distant from the crest, the bearing capacity increases. Furthermore, the results also prove that there is a clear proportional relation between relative densities –bearing capacity. The model test provides qualitative information on parameters influencing the bearing capacity of square footing. These tests can be used to check the bearing capacity estimated by the conventional methods.

Description: Tunnel construction below or adjacent to piles will affect the performance and eventually the stability of piles due to ground deformation resulting in the movement of piles and changes in the axial force distribution along the piles. A three dimensional finite element analysis using PLAXIS 3D (2013) was performed to study the behaviour of a single pile and 3 x 3 piles group during the advancement of shield tunnelling in ground. The 10-node tetrahedral elements were used to model both the soil and the tunnel lining. The Hardening Soil (HS) model was used to simulate the soil structure interaction at the tunnel-soil interface. An isotropic elastic model was used for the pile, piles cap, tunnel lining and tunnel boring machine shield (TBM). Several parametric studies were attempted including the longitudinal, lateral, and vertical tunnel location relative to pile embedded in different types of soil (clay or sand). The results showed that the pile head settlement increases during the tunnelling advancement in larger values than that for ground surface settlement. A zone of influence was determined in the range of twice the tunnel diameter in the longitudinal direction (forward and backward of the pile), and transverse direction (left and right of the tunnel centreline). If the tunnel boring is kept off this zone then there is no fear of pile collapse.

Description: The paper evaluates the effectiveness of reinforcing a damaged earth structure with making counterfort drains in its slope. The system of counterfort drains changed the soil properties significantly over a long-term use. The evaluation was based on many years of field and laboratory tests and stability analysis. The field tests concerned the observation of N WST probing resistance change, and the laboratory tests concerned the change in soil consistency and water content. The paper presents the results of tests that were conducted over 13 years.

Description: The article describes a computer analysis of the pull-out test used to calculate the force needed to pull out a rock fragment and determine the shape of this broken fragment. The analyzed material is sandstone and porphyry. The analysis included the first approach to using own subroutine in the Simulia Abaqus system, that is, which task is undertaken to accurately determine the crack path of the Finite Element Method model. The work also contains a description of laboratory tests and analytical considerations.

Description: At present, the suspended monorail systems constitute a very common means of transportation in the Polish hard coal mines. The main advantages of the suspended monorail include the independence of the route from the working floor surface irregularities and the possibility to transport cargo of significant mass and size.The masses and dimensions of machines and devices transported via monorail have increased considerably in recent times. This particularly concerns the transport of longwall system elements. In Poland, the maximum speed of suspended monorail travel is 2 m/s. Due to the fact that preparations are currently underway to increase the maximum speed above 2 m/s, it is necessary to inspect what influence it will have on work safety and mining support stability.Current operational experience and tests have shown that dynamic loads induced by the suspended monorail transportation have a significant influence on the roadway support stability, working protection durability and on the monorail operators. This is particularly true during the emergency braking of a suspended monorail by means of a braking trolley, where the overloads reach 3g.Bench tests of the selected steel arch and rock bolt support elements utilised in the Polish hard coal mines were conducted in order to determine the resistance of steel arch and rock bolt supports to static and dynamic loads.The article presents the results of the tests conducted on a steel arch support in the form of the sliding joints of an ŁP/V29 yielding roadway support, which is commonly employed in the Polish hard coal mines. Tests of elements of the threaded bolts with trapezoidal threads over the entire rod length were conducted as well.The conducted strength tests of steel arch and rock bolt support elements under static and dynamic loading have shown that dynamic loading has decisive influence on the support’s retaining of its stability. Support element stability decreases along with the increase of the impact velocity. This concerns both the steel arch support and the rock bolt support.

Description: We show that the global non-linear stability threshold for convection in a double-diffusive couple-stress fluid saturating a porous medium is exactly the same as the linear instability boundary. The optimal result is important because it shows that linearized instability theory has captured completely the physics of the onset of convection. It is also found that couple-stress fluid saturating a porous medium is thermally more stable than the ordinary viscous fluid, and the effects of couple-stress parameter (F ) , solute gradient ( S f ) and Brinkman number ( D a ) on the onset of convection is also analyzed.

Description: This paper discusses the pull-out laboratory tests and the monitoring of expansion-shell bolts with a length of 1.82 m. The bolts comprised the KE-3W expansion shell, a rod with a diameter of 0.0183 m and a profiled, circular plate with a diameter of 0.14 m, and a gauge of 0.006 m. The bolts were installed in a concrete block with a compressive strength of 75 MPa. The tests were conducted on a state-of-the-art test stand owned by the Department of Underground Mining of the AGH University of Science and Technology. The test stand can be used to test roof bolts on a geometric scale of 1:1 under static and rapidly varying loads. Also, the stand is suitable for testing rods measuring 5.5 m in length. The stand has a special feature of providing the ongoing monitoring of bolt load, displacement and deformation. The primary aim of the study was to compare the results recorded by two different measurement systems with the innovative Self-Excited Acoustic System (SAS) for measuring stress variations in roof bolts. In order to use the SAS, a special handle equipped with an accelerometer and exciter mounted to the nut or the upset end of the rod was designed at the Faculties of Mining and Geoengineering and Mechanical Engineering and Robotics of the AGH University of Science and Technology. The SAS can be used for nondestructive evaluation of performance of bolts around mining workings and in tunnels. Through laboratory calibration tests, roof bolt loads can be assessed using the in-situ non-destructive method.

Description: This paper presents an experimental investigation of the discharge flow pressure in the vertical silo and the hopper due to the use of insert (top cone with trunk cone bottom). Using the Insert inside the silos is one of the proposed solutions to avoid the problems of having funnel flow pattern, which has a significant effect on the distribution of flow pressure exerted on the silo wall and the hopper. The experiments were performed on a metal cylinder prototype; corn was used as a granular material, and the wall and hopper pressure distribution was measured by a special pressure transducer. The experiments revealed an important result in the flow pressure due to the change in the location of the insert. The experiments were conducted in Damascus University laboratories.

Description: Water seepage is one of the most important features of embankment dams. To prevent and reduce seepage, it is necessary to seal the dam. Plastic concrete cutoff walls are one of the most efficient methods in waterproofing the foundation of embankment dams on permeable alluvial substrates. Sufficient resistance to loads, low permeability to maintain dam sealing, high ductility compatible with the foundation and deformation under load without cracking are the main requirements in plastic concrete cutoff walls. In this paper, the construction and implementation of the cutoff wall of Karkheh Dam, which is one the world’s largest water sealing projects, was studied. In addition, a numerical model using Seep-3D software was developed to evaluate the efficiency of the cut-off wall to decrease the seepage over the dam’s foundation. The numerical results validated by instrumentation statistics resulted from 17-years dam operation. According to the results, after the drainage of the reservoir, the cutoff wall optimally reduced the hydraulic gradient by 0.08 from 2.35 and the water leakage by 3.1 m/s from 18.3 m/s.

Description: The main issue of the paper is the estimation of soil hydraulic permeability based on the DMT test. DMTA, DMTC and SASK methods performed in the Nielisz dam, Stegny and the SGGW Campus of the Warsaw University of Life Sciences sites are described. The article presents the implementation of the dilatometer Marchetti test (DMT) in the determination of soil fraction and effects of its occurrence in the subsoil, tested in the Nielisz dam located in the Wieprz river valley in the Lublin province, and in various sites in Warsaw (Stegny site and SGGW Campus of the Warsaw University of Life Sciences). In order to acquire the needed data, the flat dilatometer test (DMT) method was used. A direct and indirect pressure methodology of interpreting soil swelling was characterized in the article. The paper shows the possibilities of determining sand, silt and clay soil fractions based on po and p1 pressures from dilatometer tests (DMT) and the effective (σ’vo) and total (σvo) vertical in situ overburden stress. Additionally, the main advantage of this paper is the proposal of use of a new chart to determine hydraulic permeability and soil fraction, based on DMT tests.

Description: This article deals with the vibrations of a nonprismatic thin-walled beam with an open cross section and any geometrical parameters. The thin-walled beam model presented in this article was described using the membrane shell theory, whilst the equations were derived based on the Vlasov theory assumptions. The model is a generalisation of the model presented by Wilde (1968) in ‘The torsion of thin-walled bars with variable cross-section’, Archives of Mechanics, 4, 20, pp. 431–443. The Hamilton principle was used to derive equations describing the vibrations of the beam. The equations were derived relative to an arbitrary rectilinear reference axis, taking into account the curving of the beam axis and the axis formed by the shear centres of the beam cross sections. In most works known to the present authors, the equations describing the nonprismatic thin-walled beam vibration problem do not take into account the effects stemming from the curving (the inclination of the walls of the thin-walledcross section towards to the beam axis) of the analysed systems. The recurrence algorithm described in Lewanowicz’s work (1976) ‘Construction of a recurrence relation of the lowest order for coefficients of the Gegenbauer series’, Applicationes Mathematicae, XV(3), pp. 345–396, was used to solve the derived equations with variable coefficients. The obtained solutions of the equations have the form of series relative to Legendre polynomials. A numerical example dealing with the free vibrations of the beam was solved to verify the model and the effectiveness of the presented solution method. The results were compared with the results yielded by finite elements method (FEM).

Description: This paper presents the results obtained from an experimental programme and numerical investigations conducted on model tests of strip footing resting on reinforced and unreinforced sand slopes. The study focused on the determination of ultimate bearing capacity of strip footing subjected to eccentric load located either towards or opposite to the slope facing. Strip footing models were tested under different eccentricities of vertical load. The obtained results from tests conducted on unreinforced sand slope showed that the increase in eccentricity of applied load towards the slope facing decreases the ultimate bearing capacity of footing. Predictions of the ultimate bearing capacity obtained by the effective width rule are in good agreement with those proposed from the consideration of total width of footing subjected to eccentric load. The ultimate bearing capacity of an eccentrically loaded footing on a reinforced sand slope can be derived from that of axially loaded footing resting on horizontal sand ground when adopting the effective width rule and the coefficient of reduction due to the slope. When increasing the distance between the footing border to the slope crest, for unreinforced and reinforced ground slope by geogrids, the ultimate bearing capacity of footing is no more affected by the slope ground.

Description: In urban areas, the control of ground surface settlement is an important issue during shield tunnel-boring machine (TBM) tunneling. These ground movements are affected by many machine control parameters. In this article, a finite difference (FD) model is developed using Itasca FLAC-3D to numerically simulate the whole process of shield TBM tunneling. The model simulates important components of the mechanized excavation process including slurry pressure on the excavation face, shield conicity, installation of segmental lining, grout injection in the annular void, and grout consolidation. The analysis results from the proposed method are compared and discussed in terms of ground movements (both vertical and horizontal) with field measurements data. The results reveal that the proposed 3D simulation is sufficient and can reasonably reproduce all the operations achieved by the TBM. In fact, the results show that the TBM parameters can be controlled to have acceptable levels of surface settlement. In particular, it seems that moderate face pressure can reduce ground movement significantly and, most importantly, can prevent the occurrence of face-expected instability when the shield crosses very weak soil layers. The shield conicity has also an important effect on ground surface settlement, which can be partly compensated by the grout pressure during tail grouting. Finally, the injection pressure at the rear of the shield significantly reduces the vertical displacements at the crown of the tunnel and, therefore, reduces the settlement at the ground surface.

Description: This paper presents an enhanced constitutive model integrating deviatoric hardening with a modified yield surface for overconsolidated clayey soils in a general framework of Cam-clay type models. Its performance was assessed with the simulation of drained and undrained triaxial tests on three clays at different consolidation states in comparison to two critical state models. The proposed model satisfactorily estimates the shear resistance, while capturing the smooth nonlinearity of the soil response.Shear triaxial tests at constant mean pressure were performed on an overconsolidated marl to study the shear response. Their simulation attests the importance of deviatoric hardening integration.

Description: The present study investigates the onset of penetrative convection in- duced by selective absorption of radiation in a magnetic nanofluid saturated porous medium. The influence of Brownian motion, thermophoresis, and magnetophoresis on magnetic nanofluid treatment is taken into consideration. The Darcy’s model is selected for the porous medium. We conduct a linear stability analysis to examine the onset of instability and evaluate the results for two different configurations, namely, when the layer is heated from below and when the layer is heated from above. The numerical investigations are carried out by applying the Chebyshev pseudospectral method. The effect of the porosity parameter E, parameter Y (represents the ratio of internal heating to boundary heating), Lewis number Le, concentration Rayleigh number Rn, Langevin parameter αL, width of nanofluid layer d, diffusivity ratio η, and modified diffusivity ratio NA is examined at the onset of convection. The results indicate that the convection commences easily with an increase in the value of Y, Le, and NA but opposite in the case with a decrease in the value of E, αL, η and d for both the two configurations. The parameter Rn advances the onset of convection when the layer is heated from below, while delays the onset of convection when the layer is heated from above.

Description: This article presents the results of tests on the energy properties of sedimentary rocks in the Upper Silesian Coal Basin. The rocks were tested both in an air-dry state and in a water saturation state. Samples of sedimentary rocks were collected from boreholes drilled in the underground workings of coal mines located within the area of the city of Jastrzębie, in the areas of the Chwałowice Trough and Rybnik Trough (south-western part of the Upper Silesian Coal Basin) and in the Main Trough. Influence of saturation condition on the values of the tested energy parameters was observed. The values of elastic energy and dissipated energy obtained for the samples tested in water saturation were lower compared to the values obtained for samples tested in air-dry state. As observed, an increase in the values of the given types of specific energy corresponds to an increase in the uniaxial compression strength in air-dry state and in water saturation state. Results of the tests are original and they can be applied while analysing the possibility of the occurrence of some dynamic phenomena and hazards in mine workings in Carboniferous rock mass in the Upper Silesian Coal Basin, caused by mining operations.

Description: Different types of foundations are used in steel, above-ground cylindrical storage tanks for liquids. If a sand-gravel foundation is used under the entire bottom of the tank or only in the central part of the tank, settlement can be expected, and it increases after many years of operation. The paper presents the typical kinds and types of soil settlements under the bottoms of the tanks, in which different types of foundations were used. Numerical analyses of the effect of the soil settlement on the state of deformations and stresses in steel sheets of the bottom under one of the real tanks, in which different types of foundations and different cases of settlement were assumed. The results of numerical analyses indicated the possibility of evaluating the state of the soil settlement and bottom sheet deformations on the basis of simple measurements of deformations of the lower part of the tank cylinder. These measurements can be very useful in assessing the possible risk of failure of the tank bottom during each period of its operation, as measurements of settlement of the bottom of a filled tank are not feasible in practice. It has been proposed that in each steel tank, the deformation of the cylinder’s sheets should be measured even before the beginning of exploitation, and that in subsequent periodical measurements, the influence of the soil settlement under the tank on the state of the cylinder deformation and bottom’s strain should be assessed more accurately.

Description: Sands reinforced by hydraulic binders (cement) have constituted in recent decades a major asset for the expansion of several areas of engineering. The mechanical behavior of sand-cement mixtures has undergone some controversies studied on the Chlef sand. In this paper, we present an experimental study to investigate the mechanical behavior of a sandy soil reinforced by a hydraulic binder (cement), using the direct shear apparatus emphasizing on the shear strength characteristics and the vertical deformation variation of cemented reinforced sand. The parameters used in this study are mainly: relative density (Dr = 80%), normal stress (σn = 100, 200, 400 kPa), water content (3, 7 and 10%), cement content (2.5, 5, 7.5 and 10 %) and cure time (7, 14 and 28 days). The experimental results show that the mechanical characteristics in terms of internal cohesion (C) and internal frication angle (φ) give a better mechanical performance with the binder inclusion, and the cure conditions play an effective role on the improvement of the shear strength. This result also showed that 10% of the cement content gave us a maximum value of shear strength and an optimal influence on the mechanical characteristics. The addition of cement not only improves the shear strength of soil, but also provides diversity in the resistance against the deformations imposed load, which can be established by a dilatant character.

Description: Extractive industries often use explosives to destroy rocks, and productivity requirements tend to increase the charges of the explosives. The blasts induce vibrations, which result in a potential damage of the surrounding structures. Therefore, the prediction of vibrations should be described with accuracy, in order to ensure the safety of engineered structures. However, the prediction of vibrations’ levels remain a complicated issue, because it involves numerous parameters correlated to the quarry site. In this paper, statistical analysis based on the peak particle velocity (PPV) and the attenuation law has been carried out to assess the safety charges (Q) for different distances (R) between the blast and the considered structure to secure. Moreover, the experimental investigations were conducted on the quarry site of “Sococim”, which is located on the south coast of Senegal. To ensure the safety of the “Conveyor belt” and “Panel 1 (Upper exploitation level)” sites, the PPV should be less than 10 mm/s. In fact, the attenuation model has been used to assess the safe charge weights of the explosive (Q) to be used at the “Conveyor belt” site and at the “Panel 1 (Upper exploitation level)” site. Therefore, the safe charge weights per delay (Q) were respectively 116 kg and 13.75 kg.

Description: This work presents the geotechnical problems occurring in the interaction area between road embankments and the bridge structures in case a subsoil characterised by complex and complicated geological and engineering conditions. These significant problems that occur during the design, performance and exploitation of the abutment structures, are illustrated on the example of engineering practice in Lower Silesia, concerning a road embankment that constitutes access to the bridge. The results of numerical analyses concerning the process of consolidation of low-strength soils and their impact on the settlements of road embankment indicate the need to carry out such analyses also in the cases, when the soft soils occur in the direct geotechnical layer under the designed embankment. The Authors included in this article a discussion regarding other effective actions and solutions that can be used in the design and performance phase, leading to the elimination or reduction of problems concerning the connection of engineering structures with road embankments, which have been recurring for years, ultimately resulting in the improvement of quality, comfort and safety of road exploitation.

Description: Understanding the quality of intact rock is one of the most important parts of any engineering projects in the field of rock mechanics. The expression of correlations between the engineering properties of intact rock has always been the scope of experimental research, driven by the need to depict the actual behaviour of rock and to calculate most accurately the design parameters. To determine the behaviour of intact rock, the value of important mechanical parameters such as Young’s modulus (E), Poisson’s ratio (ν) and the strength of rock (σcd) was calculated. Recently, for modelling the behaviour of intact rock, the crack initiation stress (σci) is another important parameter, together with the strain (σ). The ratio of Young’s modulus and the strength of rock is the modulus ratio (MR), which can be used for calculations. These parameters are extensively used in rock engineering when the deformation of different structural elements of underground storage, caverns, tunnels or mining opening must be computed. The objective of this paper is to investigate the relationship between these parameters for Hungarian granitic rock samples. To achieve this goal, the modulus ratio (MR = E/σc) of 50 granitic rocks collected from Bátaapáti radioactive waste repository was examined. Fifty high-precision uniaxial compressive tests were conducted on strong (σc 〉100 MPa) rock samples, exhibiting the wide range of elastic modulus (E = 57.425–88.937 GPa), uniaxial compressive strength (σc = 133.34–213.04 MPa) and Poisson’s ratio (ν = 0.18–0.32). The observed value (MR = 326–597) and mean value of MR = 439.4 are compared with the results of similar previous researches. Moreover, the statistical analysis for all studied rocks was performed and the relationshipbetween MR and other mechanical parameters such as maximum axial strain $left( {{varepsilon }_{ext{a,},ext{max}}} ight)$for studied rocks was discussed.

Description: Waste material such as used tires is increasing every year, which poses environmental problems. However, such material has been used in several geotechnical applications as alternative lightweight backfill in highway embankments and/or behind retaining walls, providing environmental, economic and technical benefits. These applications require knowledge of engineering properties of soil-tire rubber mixtures. The present study aims to show the possibility of tire rubber usage in sand by evaluating the shear strength and deformability of sand mixed with granulated rubber, in weight percentages between 0 and 50%. The tire rubber content was found to influence the stress-strain and deformation behavior of the mixtures. The shear strength of sand mixed with 10% or 20% tire rubber was higher than that measured for sand only. However, the trend for TRC = 30–50% was different. Samples with a rubber content of 30-50% exhibited a rapid decrease in the stress ratio compared with that of sand. The major principal strain at maximum stress ratio was found to increase with increasing tire rubber content. However, it was observed that the lateral strains (minor and intermediate principal strains) of samples reduced significantly with the addition of tire rubber to the sand.

Description: The paper presents tests set-ups for experiments on sorption kinetics and gas filtration kinetics in a porous medium. It was observed that two phenomena occur in these processes: transportation of gas into the porous solid and settling of gas molecules on the walls of the solid or within its volume. An experiment was carried out in which a thin resistance thermometer was quickly taken out of an argon stream and placed in carbon dioxide or the other way round. The measurement made it possible to determine the sorption time constant. It was demonstrated that the sorption rate is much higher than the filtration rate. Thus, filtration is the process describing the rate at which gas molecules penetrating the porous substance are adsorbed or desorbed. The sorption time constant is not 〉50 m.In the second experiment, the author determined the rate at which gas is liberated from coal grains. The measurement method was based on measurement of the pressure of desorbing gas in constant volume. The experiment involved measurement of the pressure of the gas liberated from the coal grains in a closed chamber. The kinetic curves obtained in this way were used to determine the carbon dioxide coefficient in coal grains. During the experiment, particular focus was put on the initial stage of gas liberation (up to 0.4 s).The slower process of gas transporting in the porous structure of coal is the transporting of gas through a coal briquette. Experimentally implemented variety of boundary conditions allowed for a more complete verification of the assumed theoretical model and possibly for the exact determination of filtration parameters. The experimental set-up built for this purpose, allows for pressure and temperature measurement on the briquette side surface.

Description: In this work, the input-output method of dynamic parameters' identification is experimentally tested. A method based on the transformation of a dynamic problem into a static problem by means of integration of the input and output signal was presented. The problem discussed in this article is the identification of the coefficients of stiffness matrices and eigenfrequencies of a discrete dynamic system subjected to kinematic input. The experimental analysis was carried out on a three-storey slab-and-column structure, which constitutes a physical model of a building. The vibrations of the model were excited kinematically by an earthquake simulator. The device has a computer-controlled, movable table top, which can move independently in three directions, that is, horizontally, vertically, and rotationally around the vertical axis.The aim of the experimental studies presented in this work was to determine the dynamic parameters of the model (stiffness, natural frequencies) using the input-output method in the time domain. Moreover, the results obtained with this method were compared with the results of experimental modal analysis (EMA) in order to verify their correctness. It was assumed that the movement of the base is horizontal and occurs in one direction. Two short-term, irregular kinematic excitations of the construction were considered, and the selected results and conclusions from experimental analyses were presented in this work.

Description: The article presents the analysis of complex stress states in the concrete structure of grain silos, caused by non-centric emptying. The authors present a combination of loads from the pressure of bulk solid on the silo chamber according to Eurocode 1, Part 4 [11], which should be taken into account when emptying on large eccentricities in action assessment class 3 (AAC3) silos. For the example of a cylindrical wheat silo with a height of 25 m and a diameter of 10 m, the researchers carried out an analysis regarding the impact of the size of the eccentric discharge outlet on the distributions of forces and bending moments in a reinforced concrete wall.

Description: This paper analyses the effects of loads that change their location, i.e. moving but quasi-static loads. Displacements defining the deformation of the soil–steel structure’s shell buried in soil are calculated from the results of measurements performed using a dense grid of points located on the circumferential section of the corrugated plate. In this way, all the components of the structure, namely the corrugated plate, the backfill and the pavement with its foundation, as well as the natural (real) principles of their interaction, are taken into account in the solution. In the proposed algorithm, unit strains are converted into displacements, whereby results as accurate as the ones obtained by direct experimental measurements are obtained. The algorithm’s main advantages are that the number of points is limitless, they are regularly distributed on the circumferential section of the shell and any displacement directions can be obtained. Consequently, the deformations of the shell can be faithfully reproduced. The algorithm’s convenient feature is that one can use a simplified computational diagram of the shell in the form of a beam having the shape of the shell in 2D space (without the other components of the soil–steel structure). The advantage of this measuring method (electric resistance tensometry) is that there is no need to build the solid scaffold used for displacement measurements. The research focuses on the analysis of the displacements and the unit strains arising during the primary and secondary (return) travel of the load.

Description: In this article, the stress–dilatancy relationship for crushed latite basalt is analysed by using Frictional State Theory. The relationship is bilinear, and the parameters α and β determine these two straight lines. At the initial stage of shearing, the mean normal stress increment mainly influences breakage, but at the advanced stage, it is shear deformation that influences breakage. At the advanced stage of shearing, the parameter αpt represents energy consumption because of breakage and βpt mainly represents changes in volume caused by breakage during shear. It is also shown that breakage effect is significant at small stress levels and the η-Dp plane is important to fully understand the stress–strain behaviour of crushed latite basalt in triaxial compression tests.

Description: A three-dimensional finite element technique was used to analyse single pile lateral response subjected to pure lateral load. The main objective of this study is to assess the influence of the pile slenderness ratio on the lateral behaviour of single pile. The lateral single pile response in this assessment considered both lateral pile displacement and lateral soil resistance. As a result, modified p-y curves for lateral single pile response were improved when taking into account the influence lateral load magnitudes, pile cross sectional shape and flexural rigidity of the pile. The finite element method includes linear elastic, Mohr-Coulomb and 16-nodes interface models to represent the pile behaviour, soil performance and interface element, respectively. It can be concluded that the lateral pile deformation and lateral soil resistance because of the lateral load are always influenced by lateral load intensity and soil type as well as a pile slenderness ratio (L/D). The pile under an intermediate and large amount of loading (in case of cohesionless soil) has more resistance (low lateral displacement) than the pile embedded on the cohesion soil. In addition, it can be observed that the square-shaped pile is able to resist the load by about 30% more than the circular pile. On the other hand, pile in cohesionless soil was less affected by the change in EI compared with that in cohesive soil.

Description: Back in the early 1980s, coal deposits occurring at depths of ~700 m below surface were already regarded as large-depth deposits. Meanwhile, today the borderline depth of large-depth mining has extended to 〉1,000 m. Design, excavation and maintenance of mining roadways at the depth of 〉1,000 m have, therefore, become crucial issues in a practical perspective in recent years. Hence, it is now extremely important to intensify research studies on the influence of large depths on the behaviour of rock mass and deformation of support in underground excavations. The paper presents the results of the study carried out in five mining excavations at depths ranging from 950 to 1,290 m, where monitoring stations with measurement equipment were built. The analysis of data from laboratory and coal mine tests, as well as in situ monitoring, helped to formulate a set of criteria for stability assessment of underground excavations situated at large depths. The proposed methodology of load and deformation prediction in support systems of the excavations unaffected by exploitation is based on the criteria referring to the depth of excavation and the quality of rock mass. The depth parameter is determined by checking whether the analysed excavation lies below the critical depth, whereas the rock mass quality is determined on the basis of the roof lithology index (WL) and the crack intensity factor (n)

Description: In the study described here model calibration was performed employing the inverse analysis using genetic algorithms (GA). The objective of analysis is to determine value of the coefficient of hydraulic conductivity, k. The commonly used method for the determination of coefficient of hydraulic conductivity based on Terzaghi consolidation leads to an underestimation of the value of k as the Terzaghi model does not take into account the deformation of soil skeleton. Here, an alternative methodology based on genetic algorithms is presented for the determination of the basic parameters of Biot consolidation model. It has been demonstrated that genetic algorithms are a highly effective tool enabling automatic calibration based on simple rules. The values of the coefficient of hydraulic conductivity obtained with GA are of at least one order smaller than values obtained with the Terzaghi model.

Description: Road embankments, especially their slopes’ surfaces, must fulfil all the requirements concerning the exploitation criteria after the completion of construction works. This is very important while constructing or modernizing the embankments, based on the substrate including low-strength soils as well as in simple ground conditions (most convenient). The last dozen or so years of intensive construction of transport infrastructure have shown how big is the problem of ensuring the required volumes of qualified soil material for the construction of road embankments or the modernization of railway embankments. The depleting deposits of natural and easily accessible soils for the construction of embankments result in the need to use anthropogenic soils, for example, in the form of aggregates from the recycling of construction waste and other locally available waste materials, usually in the form of slag and ashes from the combined heat and power plants. In such cases, there’s a need to treat transportation earth structures individually in the scope of designing and quality control, because there are no applicable standard provisions in this scope.This work indicates some of these important contemporary problems of transport engineering, occurring in newly built and modernized road objects, such as the stability of road embankments based on a low-strength substrate, use of anthropogenic soils and materials originating from the recycling of concrete surfaces for the construction of road embankments.

Description: The objective of this research was to investigate the effect of adding thermally treated clay on some engineering properties of the untreated expansive clayey soil. Three expansive clayey soil samples obtained from three different sites in the south of Syria have been investigated. They were thermally treated up to three different levels (450°C, 650°C and 850°C) for 3 hours. Three replacement levels of thermally treated clay were used, i.e. 0%, 10% and 20%. The X-ray diffractometer (XRD) technique has been used to detect the crystalline and glassy phase in the clayey samples before and after the thermal treatment. Pozzolanic activity of the thermally treated clayey soil has been studied using the modified Chapelle test and the mechanical strength test at each of the temperature levels. Atterberg limits, compaction, free swell, swelling pressure and linear shrinkage have particularly been investigated. Test results revealed the positive effect of thermally treated clay when added to the natural soil. Plasticity index (PI) was reduced by about 60% when 20% thermally treated clay was added to the natural soil. In addition, 6% lime was added to further investigate the combined effect of lime and calcined clay on the properties of the clayey expansive soil. All investigated properties were significantly improved when 20% thermally treated soil and 6% lime were added together. For instance, swelling pressure and linear shrinkage values were reduced to less than 15% or even much less when compared with those of the natural soil. Scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis were employed as well.

Description: In the method of steel tank erection, consisting in assembling the roof and the next courses (segments) of the shell at the ground level, starting from the top one (the so-called hydraulic jacking-up method), the assembled part of the tank is lifted using assembly supports (towers, trestles), hydraulic jacks and ropes. Supports are located inside or outside the tank, and their bases are usually not anchored. During the assembly work, numerous contaminations can appear under the bases of the supports; therefore, boundary conditions of the system consisting of the elevated tank and assembly supports may change, influencing the field of displacements and stresses in the elements of this system. This article presents the results of numerical tests of an exemplary mounted tank – mounting support system – at various possible coefficients of friction between the bases of the supports and the ground. The influence of the support conditions on the effort of the essential elements of the system was assessed. Calculation difficulty was noted to determine the directions of horizontal responses of the supports. It was assumed that these directions did not change after exceeding the values of the friction forces. The analysed tank collapsed during its erection.

Description: Some important modern problems of the transport engineering, which occur in the newly built and modernised road objects, have been indicated in the work. A discussion was conducted regarding the methods of assessing the stability of slopes of the road embankments, the obtained stability margins and the interpretation of obtained results in the specific cases of foundations of the road earth structures. Presented observations result from analysing the stability assessments of slopes of the road embankments, which was conducted on many communication objects, characterised by high variability of foundation conditions.

Description: This paper discusses the issues associated with the influence of underground mining operations on sewage pipelines built using the pipe jacking method. At present, to build sewage pipelines, especially in urban areas and deep embedment, trenchless technologies are employed. Mainly in these technologies, pipes are jacked into a bored tunnel using hydraulic jacks. These methods are also applied in mining areas.The aim of this paper is to analyse the influence of ground deformation, caused by mining operations, on sewage pipelines built using the pipe jacking method. The type of pipelines discussed here is built with butted sections, which cannot compensate the influences of mining operations in pipe joints if horizontal compression occurs in the near-surface layer of soil. Pipelines embedded in trenches in the mining areas are secured against the influence of mining operations with expansion joints, which compensate for ground deformation. Hence, in the analysis of the influence of soil deformation caused by mining on sewage pipelines built using jacking method, special attention was paid to the performance of pipe joints. Pipelines of the type are subjected to additional loads and displacements, caused by soil deformations like horizontal strains, horizontal soil displacements and surface curvatures. We propose a way to consider the influence of mining operations on sewage pipelines built using the pipe jacking method.

Description: Diaphragm walls are deep embedded earth retaining structures. They also act as a part of the foundation. Geotechnical codes of practice from various countries provide procedures for the analysis of deep foundations. Not many standards are available that directly regulate the analysis of diaphragm walls. This paper compares the analysis of diaphragm walls performed using the foundation codes of different countries. Codes including EN 1997-1, BS 8002, BS 8004, BS EN 1538, AASHTO LRFD Bridge Design Specifications, AS 4678, AS 5100.3, Canadian Foundation Engineering Manual, CAN/CSA S6, IS 9556 and IS 4651 are chosen for the study. Numerical studies and calculations are done using the finite element software Plaxis 2d. Comparative study is performed based on the values of displacements and the forces developed. Study also evaluates the effect of differences in partial safety factors. The outcome of research emphasises the need for development of comprehensive analysis procedures.

Description: In the paper, the influence of different types of bedding and backfill soil surrounding underground sewage duct on its deformation was analysed. Impact of increased soil lateral pressure was examined by considering the construction of an embankment nearby the underground pipeline. Numerical computations of three different variants of bedding and backfill soil surrounding the pipe were carried out. Displacements and deformation of the pipe were calculated using the finite element method with adoption of elastic-perfectly plastic constitutive model of soil. Subsequent stages of the construction were taken into account. Shear strength reduction method was applied to evaluate the factor of safety of the entire system. Finally, the results and conclusions were depicted.

Description: Nonlinear soil–linear structure computational strategy is commonly accepted in the community of geotechnical engineers using advanced finite element software for solving complex soil–structure interaction problems. However, further design procedure of the structural elements is carried out using increased values of the computed elastic stress resultants. It is absolutely not clear whether this method is conservative and, therefore, whether safe or not. To tackle this problem, a fully consistent nonlinear analysis of a deep excavation protected by the diaphragm wall is analysed here. The subsoil is modelled using the Hardening Soil model, while reinforced concrete is modelled using the modified Lee–Fenves model enhanced by the Eurocode 2 (EC2)-compatible creep module, developed by the author. It is shown that the commonly used nonlinear soil–linear structure computational strategy may yield insufficient amount of reinforcement from the ultimate limit state (ULS) and serviceability limit state (SLS) points of view. A consistent and conservative method of combining fully nonlinear analysis and the rules imposed by the EC2 is proposed.

Description: Ground improvement with granular piles increases the load-carrying capacity, reduces the settlement of foundations built on the reinforced ground and is also a good alternative to concrete pile. Granular piles or stone columns are composed of granular material, such as crushed stone or coarse dense sand. An analytical approach based on the continuum approach is presented for the non-linear behaviour of the granular pile. The formulation for pile element displacement is done considering the non-homogeneity of the granular pile as it reflects the true behaviour and also accounts for the changes in the state of the granular pile due to installation, stiffening and improvement effects. The present study shows that the settlement influence factor for an end-bearing granular pile decreases with increase in the relative stiffness of the bearing stratum. The settlement influence factor decreases with increase in linear and non-linear non-homogeneity parameters for all values of relative length. For a shorter pile, the rate of decrease of the settlement influence factor is greater in comparison to that for a longer pile. Shear stress at the soil–granular pile interface reduces in the upper compressible portion of the granular pile and increases in the lower stiffer portion of the granular pile due to the non-homogeneity of an end-bearing granular pile.

Description: This paper shows an example of the grouping of piezocone penetration test (CPTU) characteristics using functional data analysis, together with the results of clustering, in the form of a subsoil rigidity model. The subsoil rigidity model was constructed based on layer separation using the proposed method, as well as the k-means method. In the construction of the subsoil rigidity model, the constrained modulus M was applied. These moduli were determined from empirical relationships for overconsolidated and normally consolidated soils from Poland based on cone tip resistance.

Description: The most important piece of road infrastructure is bridges. Wooden bridges have advanced constantly during the past decades. The trend began in Scandinavian countries but has also now gained significant ground in Russia. This research studies experimental endurance potential of the joints of the wooden beam while considering the coefficient of asymmetry of the cycle, which corresponds to the actual operating conditions. Performance analysis of the composite bars is carried out based on the experiment; the development of a special methodology for calculating the joints of wooden elements with the dowel plates for their better endurance is also introduced in this paper. The results of experimental studies on the performance of bending composite wooden bridge bars based on dowel plates operating under cyclic influences thus determine the endurance limit of wood for composite wooden bridge beams based on dowel plates. The calculation technique and interdependence of the endurance coefficient affecting the asymmetry coefficient of the bent composite wooden bridge bars on the dowel plates under cyclic loading are considered. The experimental data on the endurance of composite wooden bridge beams have been obtained, and separate analysis has been made of the compounds under cyclic loading performance; a method has been developed for calculating the bent composite wooden bridge bars reinforced by the dowel plates under cyclic influences.

Description: Knowledge of the mechanical behaviour of ballast is very important for designing a railway track, especially for high-speed lines. The monotonic drained triaxial tests of scaled and fouled ballast presented in literature were analysed using the Frictional State Theory. The stress–plastic dilatancy relationship shows that four characteristic stages of shearing may be specified. The influence of stress level and water content may be quantified by the use of the Frictional State Theory.

Description: A systematic approach to measure the differences between Mohr-Coulomb (MC) and Drucker-Prager (DP) shear strength criteria used commonly in soil and rock mechanics is presented. It is shown that the DP criterion generates a shear strength between 0.6 and 3 times the MC strength, for the same friction angle and cohesion parameters. The appropriate conditions for obtaining equal shear strengths are given. Moreover, some new DP failure surfaces are proposed which minimize the differences relative to the MC predictions. The equivalence of the DP and MC criteria under plane strain conditions is also examined.