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  • Articles  (398)
  • Engineering General  (351)
  • Microbial biomass  (47)
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  • J24
  • J31
  • 1990-1994  (398)
  • Geosciences  (398)
  • 1
    Electronic Resource
    Electronic Resource
    Effect of bamboo harvest on dynamics of nutrient pools, N mineralization, and microbial biomass in soil (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 137-142 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Bamboo savanna ; N mineralization ; Nutrient pools ; Temporal variations ; Nitrification
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of harvesting bamboo savanna on the dynamics of soil nutrient pools, N mineralization, and microbial biomass was examined. In the unharvested bamboo site NO inf3 sup- -N in soil ranged from 0.37 to 3.11 mg kg-1 soil and in the harvested site from 0.43 to 3.67 mg kg-1. NaHCO3-extractable inorganic P ranged from 0.55 to 3.58 mg kg-1 in the unharvested site and from 1.01 to 4.22 mg kg-1 in the harvested site. Over two annual cycles, the N mineralization range in the unharvested and harvested sites was 0–19.28 and 0–24.0 mg kg-1 soil month-1, respectively. The microbial C, N, and P ranges were 278–587, 28–64, and 12–26 mg kg-1 soil, respectively, with the harvested site exhibiting higher values. Bamboo harvesting depleted soil organic C by 13% and total N by 20%. Harvesting increased N mineralization, resulting in 10 kg ha-1 additional mineral N in the first 1st year and 5 kg ha-1 in the 2nd year following the harvest. Microbial biomass C, N and P increased respectively by 10, 18, and 5% as a result of bamboo harvesting.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336460
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  • 2
    Electronic Resource
    Electronic Resource
    Grazing and plant-canopy effects on semiarid soil microbial biomass and respiration (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 155-162 
    Details
    ISSN: 1432-0789
    Keywords: Grazing ; Semiarid soils ; Shrubland ; Grassland ; Microbial biomass ; Microbial respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The major objectives of this study were to determine the influence of grazing on the soil microbial biomass and activity in semiarid grassland and shrubland areas and to quantify the canopy effect (the differences in soil microbial biomass and activities between soils under plant canopies and soils in the open between plants). We also quantified changes in microbial biomass and activity during seasonal transition from dry to moist conditions. Chronosequences of sites withdrawn from grazing for 0, 11, and 16 years were sampled in a grassland (Bouteloua spp.) area and a shrubland (Atriplex canescens) area on and near the Sevilleta National Wildlife Reguge in central New Mexico, USA. Samples were obtained from beneath the canopies of plants (Yucca glauca in the grassland and A. canescens in the shrubland) and from open soils; they were collected three times during the spring and summer of a single growing season. Organic C, soil microbial biomass C, and basal respiration rates (collectively called the “soil C triangle”) were measured. We also calculated the microbial: organic C ratio and the metabolic quotient (ratio of respiration to microbial C) as measures of soil organic C stability and turnover. Although we had hypothesized that individual values of the soil C triangle would increase and that the ratios would decrease with time since grazing, differences in microbial parameters between sites located along the chronosequences were generally not significant. Grazing did not have a consistion effect on organic C, microbial C, and basal respiration in our chronosequences. The microbial: organic C ratio and the metabolic quotient generally increased with time since grazing on the shrubland chronosequence. The microbial: organic C ratio decreased with time since grazing and the metabolic quotient increased with time since grazing on the grassland chronosequence. The canopy effect was observed at all sites in nearly all parameters including organic C, microbial C, basal respiration, the microbial: organic C ratio, and the metabolic quotient which were predominantly higher in soils under the canopies of plants than in the open at all sites. Microbial biomass and activity did not increase during the experiment, even though the availability of moisture increased dramatically. The canopy effects were approximately equal on the shrubland and grassland sites. The microbial: organic C ratios and the metabolic quotients were generally higher in the shrubland soils than in the grassland soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336463
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  • 3
    Electronic Resource
    Electronic Resource
    Effects of the herbicide imazethapyr on soil microbial biomass and various soil enzyme activities (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 237-240 
    Details
    ISSN: 1432-0789
    Keywords: Catalase ; Dehydrogenase ; Fluorescein diacetate hydrolase ; Imazethapyr ; Microbial biomass ; Protease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of imazethapyr, an imidazolinone derivative on the soil microbial biomass was investigated in a clay loam soil. Imazethapyr was applied in a field trial at the recommended field rate for soybean weeding, 50 g a.i. ha-1. In laboratory experiments the herbicide was incorporated at the field rate and 10-fold and 100-fold higher. In both the field trials and the laboratory experiments, the field rate of imazethapyr had no adverse effects on the microbiological processes tested. But at 10-fold and 100-fold higher rates, the herbicide decreased the biomass-C content and dehydrogenase activity and increased the hydrolytic capacity and protease and catalase activity. These findings suggest that there may be a risk in monocultural practices that require repeated herbicide treatments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336329
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  • 4
    Electronic Resource
    Electronic Resource
    Fumigation-extraction and substrate-induced respiration derived microbial biomass C, and respiration rate in limed soil of Scots pine sapling stands (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 301-308 
    Details
    ISSN: 1432-0789
    Keywords: Basal respiration ; Fumigation ; extraction ; Humus layer ; Lime ; Microbial biomass ; Pinus sylvestris L. ; Storage ; Substrate-induced respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effect of liming on microbial biomass C and respiration activity was studied in four liming experiments on young pine plantations. One of the experimental sites had been limed and planted 12 years before, two 5 years before, and one a year before soil sampling. The youngest experimental site was also treated with ash fertilizer. Liming raised the pHKCl of the humus layer by 1.5 units or less. Microbial biomass was measured using the fumigation-extraction and substrate-induced respiration methods. Liming did not significantly affect microbial biomass C, except in the experiment which had been limed 11 years ago, where there was a slight biomass increase. Basal respiration, which was measured by the evolution of CO2, increased in the limed soils, except for the youngest experiment, where there was no effect. Ash fertilization raised the soil pHKCl by about 0.5 unit, but did not influence microbial biomass C or basal respiration. Fumigation-extraction and substrate-induced respiration derived microbial biomass C values were correlated positively with each other (r=0.65), but substrate-induced respiration gave approximately 1.3 times higher results. In addition, the effect of storing the soil samples at +6 and -18°C was evaluated. The effects were variable but, generally, the substrate-induced respiration derived microbial biomass C decreased, and the fumigation-extraction derived microbial biomass C and basal respiration decreased or were not affected by storage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00383986
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  • 5
    Electronic Resource
    Electronic Resource
    Microbial biomass, N mineralization, and the activities of various enzymes in relation to nitrate leaching and root distribution in a slurry-amended grassland (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 7-12 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Soil enzymes ; N mineralization ; Grassland soils ; Nitrogen leaching ; Root growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract High rates of cattle slurry application induce NO inf3 sup- leaching from grassland soils. Therefore, field and lysimeter trials were conducted at Gumpenstein (Austria) to determine the residual effect of various rates of cattle slurry on microbial biomass, N mineralization, activities of soil enzymes, root densities, and N leaching in a grassland soil profile (Orthic Luvisol, sandy silt, pH 6.6). The cattle slurry applications corresponded to rates of 0, 96, 240, and 480 kg N ha-1. N leaching was estimated in the lysimeter trial from 1981 to 1991. At a depth of 0.50 m, N leaching was elevated in the plot with the highest slurry application. In October 1991, deeper soil layers (0–10, 10–20, 20–30, 30–40, and 40–50 cm) from control and slurry-amended plots (480 kg N ha-1) were investigated. Soil biological properties decreased with soil depth. N mineralization, nitrification, and enzymes involved in N cycling (protease, deaminase, and urease) were enhanced significantly (P〈0.05) at all soil depths of the slurry-amended grassland. High rates of cattle slurry application reduced the weight of root dry matter and changed the root distribution in the different soil layers. In the slurry-amended plots the roots were mainly located in the topsoil (0–10 cm). As a result of this study, low root densities and high N mineralization rates are held to be the main reasons for NO inf3 sup- leaching after heavy slurry applications on grassland.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336437
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  • 6
    Electronic Resource
    Electronic Resource
    Impact of pasture contamination by copper, chromium, and arsenic timber preservative on soil microbial properties and nematodes (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 71-79 
    Details
    ISSN: 1432-0789
    Keywords: Heavy metals ; Microbial biomass ; Respiration ; Enzymes ; Denitrification ; Dimethyl sulphoxide reduction ; Nematodes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microbial properties and nematode abundance were measured along a gradient of increasing Cu, Cr, and As concentrations (50–1300 mg Cr kg-1) in the top 5 cm of a pasture soil contaminated by runoff of preserving liquor from an adjacent timber-treatment plant. Microbial biomass C and N were significantly (P〈0.05) lower in contaminated than uncontaminated soils. The amount of microbial biomass C as a percentage of total organic C declined significantly (r 2 value with Cr 0.726*) with increasing contamination, and the ratio of respired C to biomass C was significantly (P〈0.05) higher with contamination. Substrate-induced respiration, microbial biomass P, and denitrification declined (r2 value with Cr 0.601, 0.833*, and 0.709*, respectively) with increasing contamination. Increasing contamination had no effect on prokaryote substrate-induced respiration but eukaryote: eukaryote substrate-induced respiration declined significantly (r 2 value with Cr 0.722*). Accordingly, the ratio of prokaryote substrate-induced respiration increased significantly (r 2 value with Cr 0.799*) with contamination. There was a significant (r 2 value with Cr 0.872*) hyperbolic relationship between sulphatase activity and contamination, with activity declining by approximately 80% at 〉1000 mg Cr kg-1. Increasing contamination had no effect on basal respiration, dimethyl sulphoxide reduction, and phosphatase, urease, and invertase activities. Numbers of plant-associated nematodes declined significantly (r 2 value with Cr 0.780*) with contamination. On a percentage basis, plant-feeding nematodes predominated in less contaminated soils, whereas bacterial-feeding and predatory nematodes predominated in heavily contaminated soils. The use of the fumigation—incubation procedure for measurement of microbial biomass C in heavy-metal contaminated soils is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336448
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  • 7
    Electronic Resource
    Electronic Resource
    Near-infrared characteristics of forest humus are correlated with soil respiration and microbial biomass in burnt soil (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 80-82 
    Details
    ISSN: 1432-0789
    Keywords: Biological variation ; Coniferous forest ; Near-infrared spectrum ; Partial least-square regression ; Microbial biomass ; Soil respiration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Near-infrared spectroscopy and soil physicochemical determinations (pHH2O, organic matter content, total C content, NH inf4 sup+ , total N content, cation-exchange capacity, and base saturation) were used to characterize fire-or wood ash-treated humus samples. The spectroscopic and the soil physicochemical analysis data from the humus samples were used separately to explain observed variations in soil respiration and microbial biomass C by partial least-square regression. The first regression component obtained from the physicochemical and spectroscopic characterization explained 10–12% and 60–80% of the biological variation, respectively. This suggests that information on organic material collected from near-infrared spectra is very useful for explaining biological variations in forest humus.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336449
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  • 8
    Electronic Resource
    Electronic Resource
    Microbial mineralization of atrazine and 2,4-dichlorophenoxyacetic acid in riparian pasture and forest soils (1994)
    Springer
    Biology and fertility of soils 18 (1994), S. 89-94 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Atrazine ; 2,4D ; Riparian soils ; Iodo-nitrotetrazolium chloride stain ; Epifluorescence microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Microbial biomass and mineralization of atrazine [2-chloro-4(ethylamino)-6(isopropylamino)s-triazine] and 2,4-D (2,4-dichlorphenoxyacetic acid) were examined in the top 10 cm of riparian pasture soils and in the litter layer and top 10 cm of mineral soils of riparian forest ecosystems. The riparian forest litter had higher levels of active and total fungal biomass than forest or pasture mineral soils in winter, spring, and fall. Active bacterial biomass was higher in forest litter than in forest and pasture mineral soils in spring and autumn, and higher in forest mineral soils than in pasture soils in summer. Total bacterial biomass was higher in forest mineral soils than in pasture soils during all seasons. In spring, it was also higher in forest litter than in pasture soils. Atrazie and 2,4-D mineralization in pasture soils was exceeded by that in forest litter in spring and autumn and by that in forest mineral soils in summer and autumn. There was no correlation between either active or total fungal and bacterial biomass with pesticide degradation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336451
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  • 9
    Electronic Resource
    Electronic Resource
    Effects of pasture improvement and intensive cultivation on microbial biomass, enzyme activities, and composition and size of earthworm populations (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 185-190 
    Details
    ISSN: 1432-0789
    Keywords: Earthworms ; Enzyme activity ; Microbial biomass ; Pasture ; Soil organic matter
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated the quantity and distribution of organic C, microbial biomass C, protease, arylsulphatase and arylphosphatase activity, and earthworm numbers and biomass in the soil from a 37-year-old grazed pasture supplied with superphosphate at rates of 0, 188, and 376 kg ha-1 annually. The results were compared with a non-irrigated wilderness site which had not been used for agriculture and an arable site that had been intensively cultivated for 11 consecutive years. In the 0- to 5-cm layer, organic C followed the trend arable〈wilderness = control〈low phosphate = high posphate and soil biological activity generally followed a similar trend. For example, protease and arylsulphatase activity and microbial biomass C followed the order arable〈wilderness〈control〈low phosphate = high phosphate. The greater activity in the control than the wilderness site was attributed to the more regular turnover of organic matter throughout the year in the control due to the activity of the grazing animals. Earthworm numbers increased in the order arable〈wilderness〈control〈low phosphate〈high phosphate. In the improved pasture sites the earthworm population was dominated by Aporrectodea caliginosa (77–89% of total numbers) although Lumbricus rubellus made an increasing contribution to the population with increasing superphosphate rates. In the unirrigated wilderness site the population consisted of 56% A. caliginosa and 44% L. rubellus. While Octolasion cyaneum and A. rosea made up a small proportion of the population in the improved pasture sites, they were not present in the wilderness or arable sites. A. caliginosa was the only species present in the arable site. The mean fresh weight of individuals followed the order arable〈control = low phosphate = high phosphate〈wilderness and the proportion of jeveniles in the population was greatest in the arable and lowest in the wilderness site.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336320
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  • 10
    Electronic Resource
    Electronic Resource
    Carbon and nitrogen turnover in two acid forest soils of southeast Australia as affected by phosphorus addition and drying and rewetting cycles (1994)
    Springer
    Biology and fertility of soils 17 (1994), S. 212-218 
    Details
    ISSN: 1432-0789
    Keywords: Mineralization ; Microbial biomass ; Drying and rewetting ; P addition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects of adding P and of drying and rewetting were studied in two acid forest soils from southeast Australia. The soils were a yellow podzolic with a low soil organic matter content (3.75% C) and a red earth with a high organic matter content (13.5% C). C and N mineralization and microbial C and N contents were investigated in a laboratory incubation for 151 days. Microbial C and N were estimated by a hexanol fumigation-extraction technique. Microbial C was also determined by substrate-induced respiration combined with a selective inhibition technique to separate the fungal and the bacterial biomass. The results obtained by the selective inhibition technique were not conclusive. Adding P to the soil and drying and rewetting the soil reduced microbial N. This effect was more pronounced in rapidly and frequently dried soils. Microbial C was generally less affected by these treatments. Compared with the control, the addition of P caused a reduction in respiration in the red earth (-13%) but an increase in the yellow podzolic soil (+12%). In the red earth net N mineralization was highest following the addition of P. In the yellow podzolic soil highest N mineralization rates were obtained when the soil was subjected to drying and rewetting cycles. In both soils increased N mineralization was associated with a decrease in microbial N, indicating that the mineralized N was of microbial origin. Nitrification decreased with rapid drying and rewetting. The addition of P promoted heterotrophic nitrification in both soils.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00336325
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  • 11
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180201
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  • 12
    Electronic Resource
    Electronic Resource
    On overestimation of displacements in numerical calculation of zoned dams (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 1-24 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Overestimation of displacements in numerical calculations can occur if some requirements are not met by the constitutive relations. Along with consideration for small strain behaviour of soils1 the stiffening effects of unloading in shear should be taken into account. The latter problem is analysed in the paper using embankment dams as a typical example. Strain and stress paths in their cores and shells were derived from field measurement results and frequent path direction changes during seemingly monotonic loading process were discovered. Proportional loading test results of isotropically and anisotropically consolidated sand allowed interpretation of the in situ paths by the incremental theory of plasticity and distinction between the sections where unloading and reloading in shear develop. Furthermore, the analysis of these tests showed a marked stiffening of the soil due to unloading as well as neutral loading in shear. The strain redistribution due to material inhomogeneity, either inherent or introduced by the loading process, was identified as a common reason for the frequent occurrence of this phenomenon. Consequently, overestimations in displacement calculations can be brought about by neglecting this important effect by the constitutive model used. Accordingly, the unit response envelopes of some typical constitutive laws have been checked from this special point of view, and the models properly describing this phenomenon selected.
    Additional Material: 21 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180102
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  • 13
    Electronic Resource
    Electronic Resource
    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180101
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  • 14
    Electronic Resource
    Electronic Resource
    Dual-porosity behaviour of naturally fractured reservoirs (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 359-376 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A dual-porosity model based on the modified formulation by Barenblatt et al. has been presented for the simulation of naturally fractured reservoirs. It is shown that neglecting terms in the flow governing equations may not be justified for some particular physical circumstances. The analytical solution of the proposed dual-porosity model for a finite naturally fractured reservoir subjected to a constant outer boundary pressure is obtained using the Hankel transform technique while taking into account the transient flow in the matrix blocks. Both solution accuracy and efficiency are achieved utilizing an optimized algorithm when solving the inherent Bessel functions. This research indicates that the transient fluid pressure profiles in naturally fractured reservoirs are critically controlled by the permeability ratio between matrix and fractures, and by the compressibilities of fluid, fractures and solid grains. The fluid pressure change is substantially delayed if the permeability ratio becomes increasingly smaller. The dual-porosity behaviour is most obvious when the compressibility of the fractures decreases relative to the increases of compressibility of the solid grains.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180602
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  • 15
    Electronic Resource
    Electronic Resource
    Analysis of ‘infinitely long’ excavations using finite and boundary elements (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 417-426 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The paper deals with the analysis of excavations which are very long and can, for all practical purposes, be considered to be infinitely long. Special infinite finite and boundary elements are developed for the modelling of the infinitely long part of such excavations. Test examples are presented which show the accuracy which can be obtained by using these elements. Finally, examples of application in mining and petroleum engineering are shown.
    Additional Material: 6 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610180605
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  • 16
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    Analysis of compressible axially loaded piles in rock (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 427-437 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Analytical solutions are developed for the prediction of the load-settlement response of a compressible axially loaded cast in situ pile in rock. The principal input parameters are derived from the τ-z curve which applies to the contact zone between the pile shaft and the embedment material. For larger diameter piles in rock, these τ-z curves can differ markedly from curves that apply to piles in clay and may include a significant strain hardening region prior to reaching peak strength. In addition to the complete analyses which would normally require the use of a computer, simplified solutions suitable for hand calculations have been derived for the peak load and the pile head displacement to peak. An example of the application of these simplified design calculations is presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180606
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  • 17
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 519-522 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180706
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  • 18
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    Analysis of fully coupled thermomechanical behaviour around a rigid cylindrical heat source buried in clay (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 177-203 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The problem of fully coupled consolidation and heat flow around a rigid cylindrical heat source buried in clay has been studied. The governing equations of the problem are summarized in the paper and a finite element time-marching scheme to obtain an approximate solution to the governing equations is described. The stress-strain behaviour of the skeleton of the saturated soil has been represented by both a linear elastic model and the modified Cam clay soil model. The results of a limited parametric study are presented with the aim of understanding the major mechanisms of soil behaviour close to buried canisters of hot radioactive waste. A range of soil properties has been included in the study, and the effects of soil disturbance during canister emplacement have also been considered.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180304
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  • 19
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    Finite layer analysis of the behaviour of a raft on a consolidating soil (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 237-251 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A numerical method is developed in this paper for the analysis of the behaviour of a raft resting on a consolidating soil. The response of the raft under an applied loading is determined using the finite layer method for the soil and the finite element method for the raft. By considering deflection compatibility on the contact surface, the distribution of contact pressure is computed at various time steps. The settlement and bending moment in the raft is then evaluated by applying the calculated contact pressure back to the raft. It is shown that, in some cases, the maximum moment in the raft occurs during consolidation and that checking the final moment in the raft by use of elastic theory may not be sufficient.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180501
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180301
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    Considering the effect of body force for regional land displacements (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 145-160 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: In this study, a general mathematical model was developed for land displacements that occur as a result of the pressure decline in confined and/or phreatic aquifers. Two equations were developed by employing the equilibrium (force balance) equation and the flow equation in a deforming aquifer system. Both of these equations were integrated over the thickness of the aquifer system once a regional model had been formulated. The change of the body force in saturated and unsaturated zones of aquifers was considered in the derivation of the equilibrium equation. It was assumed that no external loading or force acting on the aquifer system was present. Two coupled equations expressed in terms of the averaged dilation and pressure were then obtained. The pumping data sets given in the papers of Bear and Corapcioglu1,2 in 1981 and 1983 were analysed. Drawdown and displacements in a confined aquifer were demonstrated to be identical to those estimated by Bear and Corapcioglu.1 In the case of a phreatic aquifer, however, the results estimated by the present approach were slightly different from those obtained by Corapcioglu and Bear.2 The discrepancies in the results are possibly due to errors in the equations presented by Corapcioglu and Bear.2 The present approach was able to avoid several assumptions and complex procedures used by Bear and Corapcioglu,1,2 especially in the case of a phreatic aquifer, by taking into account the change in the body force.
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    CLoE, a new rate-type constitutive model for geomaterials theoretical basis and implementation (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 253-278 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The paper describes the basic ideas and the main features of a new class of constitutive laws, in the framework of incrementally non-linear constitutive equations. CLoE is a generic name for that new class of laws, with reference to consistency at the limit surface, and explicit localization analysis. A top-down analysis of the model is presented, and illustrated by examples.
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    Letters to the editor (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 279-282 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Additional Material: 3 Ill.
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    Influence of subsurface fractures on surface deformation of an elastic half-space (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 287-303 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The paper presents a solution for calculation of the surface uplift field of a semi-infinite elastic solid embedded with a pressurized elliptical crack oriented at any angle, and at any depth. The results presented are those for a uniform pressure loading on the crack face, simulating a static pressurized hydraulic fracture, but the mathematical technique developed can be extended directly to non-uniform normal loads or general shear loads in the form of a polynomial up to the third order. The result of a special case of the new solution, where the crack is penny shaped and parallel to the free surface, is compared with results from Sun's solution and from experiments which were designed and performed by the authors. The experiments involved pressurization of a penny-shaped crack in a polyurethane material which is linear elastic under low stresses, and measurement of surface deformation by holographic interferometry and Fizeau interferometry. The correspondence between theory and experiment is excellent.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180601
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    Cyclic mobility behaviour of sand by the three-dimensional strain space multimechanism model (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 397-415 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The cyclic mobility behaviour of sand by the three-dimensional (3-D) strain space multimechanism model based on the micromechanics of granular material is investigated. The constitutive properties are characterized by the volumetric and shear mechanisms for the initial isotropic soil. The 3-D shear mechanism is decomposed into a number of microscopic plane-strain shear mechanisms in various orientations, each of which in turn consists of a number of microscopic simple shear mechanisms. Using an appropriate summation of mechanisms, the total deformation behaviour can be obtained by evaluating contributions from each mechanism. Based on the some assumptions, the dilatancy model proposed by Iai et al.1 is extended from the two-dimensional (2-D) space to the 3-D space. Comparisons of theoretically predicted results are made with experimental measurements.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610180701
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    Cracking in clays: Solutions to problems in earth structures (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 467-484 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Methods are presented for analysing earth structures subjected to tensile stresses that may produce cracking. The linear elastic fracture mechanics approach is emphasized. Methods of solution are proposed for cracking of a clay layer above the water table due to desiccation; cracking of layered earth structures subjected to external loads; cracking of clay caps for landfills due to differential settlement; and radial cracking in pressurized boreholes. Causes and mechanisms of cracking are discussed for each problem and models pertinent to each problem are proposed. Solutions have been developed by synthesizing analytical and numerical methods. Published experimental data have been incorporated in modelling matric suction and cracked beams on elastic foundations. Finite element analyses were employed to obtain solutions for cracking due to differential settlement and radial cracking in boreholes. The solutions presented herein can be used to assess the soundness of existing structures or to assess the risk of cracking for the design of new structures.
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    Calculation of the critical height of a homogenized reinforced soil wall: A numerical approach (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 485-505 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper is devoted to the stability analysis of a vertical embankment in reinforced soil, assuming that a very large number of reinforcements are periodically distributed throughout the soil mass. The reinforced soil is modelled as a homogeneous medium that obeys a macroscopic yield condition.Two numerical formulations of the homogenized problem, derived from the lower and upper bound theorems of limit analysis, respectively, with a finite element discretization technique, are described. They both lead to a linear programming problem, which is carried out by means of XPRESS industrial LP code.The practical implementation of both the static and kinematic finite element programs on the case of a vertical reinforced earth wall results in close estimates of its failure height, which are in good agreement with available experimental data. This points to the ability of such programs to provide a rigorous evaluation of the limit loads of structures through the determination of lower bound and upper bound estimates sufficiently close to each other.
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    Elastic stress waves in rockbolts subject to impact loading (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 121-131 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Due to rock bursting or blasting, violent rock ejections can occur. In underground excavations, rockbolts are often used to retain rock blocks that otherwise would be ejected. Employing the stress wave approach, general formulae are derived to compute the elastic stress waves in rockbolts subject to rock block impact loading. Weight-drop tests on steel rods, simulating impact loading of rockbolts, were performed, and a reasonable agreement is found between theoretical predictions and experimental results. The elastic stress wave in an impact loaded steel rod consists of a rider wave and a lower-frequency carrier wave. With the same drop height, the carrier wave becomes more sinusoidal as the mass ratio of steel rod to drop weight is decreased.
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    Thermodynamical approach for CamClay-family models with Roscoe-type dilatancy rules (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 133-138 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The CamClay model has been extensively used in numerous research programmes for constitutive modelling in Soil Mechanics during the past quarter of a century. Several derivations of this model are now available and routinely used for numerical simulations in the geomechanical engineering field. However, to the authors' knowledge the thermodynamical basis of this model in its original form has never been established, at least in a modern thermodynamics framework. The thermodynamics principle proposed by Ziegler is very expedient for this purpose as the non-associated flow rule may be considered. This approach is applied to the CamClay model with the Roscoe dilatancy rule. A dissipation function and free energy are specified in terms of kinematic variables (i.e. state and internal variables), and the material response is derived entirely from these functions.
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    Solving large-scale problems in mechanics: The development and application of computational solution methods (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 139-140 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    URL: http://dx.doi.org/10.1002/nag.1610180207
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    Amplification of vertically propagating SH waves by multiple layers of Gibson soils (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 205-212 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Using the Haskell-Thomson transfer matrix approach, an analytical solution is obtained for SH wave amplification by multiple layers of Gibson soils (i.e. viscoelastic layers with linearly varying shear moduli). Amplification spectra for typical soil and basement rock properties are calculated. A comparison of the Gibson soil response with that obtained for homogeneous soil models shows generally stronger amplifications associated with the Gibson soil.
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    A semi-analytical method for the wave-induced seabed response (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 213-236 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A general semi-analytical method is presented for the analysis of seabed response under wave action during a storm. The seabed is idealized as a poro-elastic medium filled with a single compressible fluid with anisotropic flow. The coupled process of fluid flow and deformation of soil skeleton is formulated in the framework of Biot's theory.The analysis for the response of homogeneous seabed of finite thickness under a plane progressive wave is developed first, followed by an extension for the case of a layered seabed. A generalization for three-dimensional response of seabed is also developed for a general wave field which provides the analyses for seabed response under short-crested or standing waves in the vicinity of a structure. Some numerical examples illustrating the proposed analyses are also presented.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 283-285 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610180406
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    Conformal analysis of seepage below a hydraulic structure with an inclined cutoff (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 345-353 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Conformal mapping techniques are used to obtain an exact solution for seepage flow below a hydraulic structure founded on permeable soil of infinite depth for a flat floor with an inclined cut-off at the downstream end. Results are presented for different values of b/s and θ. The exit gradient decreases considerably along a distance beyond the floor end with an increase in cut-off inclination. The maximum exit gradient decreases for θ = 10, 20 and 30° and starts increasing for θ = 45°. The uplift pressure decreases as θ increases. It is concluded that using an inclined cut-off increases the factor of safety in design against uplift and piping.
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    Numerical modelling of transient contaminant migration problems in infinite porous fractured media using finite/infinite element technique. Part II: Parametric study (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 543-564 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Using the numerical model presented in the first paper of this research,1 a parametric study has been carried out in this paper to investigate the effect of several important parameters on the transient contaminant transport in infinite porous fractured media. From the related numerical results, it has been demonstrated that: (1) transmissive coefficient between the porous block and the fissured network has a significant influence on the value of the concentration but has little effect on the speed of contaminant transport; (2) porosities in the porous block and fissured network have a significant influence on the maximum value of the concentration; (3) average linear velocity of flow has a significant influence on both the concentration distribution and speed of contaminant transport; (4) dispersion coefficient of the medium affects not only the shape of the concentration versus time curve but also the peak value of the concentration.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180901
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    Simulation of arch dam - foundation interaction with a new friction interface element (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 601-617 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A new model for three-dimensional non-linear contact problems with irreversible friction is presented here for the interaction between the rock foundation and an arch dam structure. Based on the finite element method and load incremental theory, a constraint contact element with displacements and contact stresses as node parameters is developed. In this approach, four contact conditions are considered, i.e. fixed, slip, free and mixed. This model can simulate frictional slippage, decoupling and re-bonding of two bodies initially mating at a common interface or with any initial gaps. Furthermore boundary conditions for this element are discussed and treatment measures proposed. This method is shown to be effective and to have the advantage of being easily implemented into standard finite element programs. Solutions are obtained for a centrally loaded, simply supported composite beam and for an end-loaded elastica with initial gaps in regional contact with a rigid surface. The results obtained for these examples are compared to the plane stress solutions by contact friction analysis. As an application example, Quanshui arch dam located in Ruyuan County of Guangdong Province in southern China is simulated with the new element.
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    Finite element modelling for simulating the surface subsidence above a compacting hydrocarbon reservoir (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 619-639 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The surface subsidence above a compacting saturated oil reservoir is the main topic of this paper. From a literature review, it is obvious that extensive efforts have been conducted for investigating this phenomenon in various situations. Herein, a numerical model, based on the finite element method, was used for simulating three-dimensional three-phase fluid flow in a deforming saturated oil reservoir. The mathematical formulation describes a fully coupled governing equation system which consists of the equilibrium and continuity equations for three immiscible fluids flowing in a porous media. An elastoplastic soil model, based on a Mohr Coulomb yield surface, was utilized. The finite element method was applied to obtain simultaneous solutions to the governing equations where the displacements and the fluid pressures are the primary unknowns. The final discretized equations are solved by a direct solver using fully implicit procedures. A linear analysis was used to study the stability conditions of the present model. Finally, a series of simulations were conducted to indicate the validity and the utility of the developed model.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 442-444 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    Elastoplastic analysis of jointed rocks using a coupled finite element and boundary element method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 445-466 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper presents a coupled, elastoplastic, finite element and boundary element method for the two-dimensional, non-linear analysis of anisotropic jointed rock. The non-linear and anisotropic behaviour of a jointed rock mass is simulated by representing the mass as an equivalent anisotropic, elastoplastic continuum, so that the influence of the jointing system is ‘smeared’ across the continuum, i.e. the individual joints are not modelled as discrete entities. Numerical examples have been solved to verify the capability, accuracy and efficiency of the present technique. The proposed technique has also been applied to the analysis of tunnel excavation problems in plane strain. The effects of anisotropy and non-linearity of the jointed rock mass during excavation have been investigated in some detail.
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    Finite element modelling of rock-socketed piles (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 25-47 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Rock socketed piles have a number of features which differentiate them from other types of piles. The generally stubby geometry leads to more even distribution of capacity between shaft and base. However, the low ratio of pile modulus to rock modulus leads to high compressibility and this, coupled with a tendency for the load transfer response along the shaft to exhibit strain-softening, gives rise to an overall response where the shaft capacity may be fully mobilized, and potentially degraded, before significant mobilization of base load.The paper presents results of finite element analyses of the response of rock-socketed piles, with particular attention to the shaft response with and without intimate base contact. The shaft interface uses a model, developed from principles of tribology, that includes dilation (and strain-hardening) prior to peak shaft friction, followed by strain-softening at larger displacements. The results of the study are shown to be consistent with field measurements, and to capture effects of the absolute pile diameter on the peak shaft friction. It is also shown that intimate base contact mitigates significantly the degree of strain-softening of the shaft response.
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    An approximate numerical analysis of pile-raft interaction (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 73-92 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper presents an approximate method of numerical analysis of piled-raft foundations in which the raft is modelled as a thin plate and the piles as interacting springs of appropriate stiffness. Allowance is made for the development of limiting pressures below the raft and of the ultimate axial load capacity of the piles.Comparisons between this analysis and existing solutions verify that, despite the approximations involved, the analysis can provide solutions of adequate accuracy for the settlement and pile load distribution within a piled raft.Comparisons are also made with the results of a series of centrifuge tests and with measurements of the performance of a full-scale piled raft. In both cases, the analysis predicts very well the settlement and proportion of load carried by the piles.
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    A generalised D matrix for anisotropic elastic granular media (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 107-120 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A matrix relating stress and elastic strain tensors for anisotropic particulate materials has been derived. The magnitude of the matrix depends on the state of the material anisotropy. Anisotropy in granular materials depends on strain because normal and tangential particle contact forces, as well as the spatial distribution of the contacts, vary with stress and strain. However, the rotation tensor and the strain tensor cannot be independent; they must satisfy certain constraints to meet the requirement for macroscopic stress tensor symmetry. These conditions and constraints lead to the derivation of the matrix presented in this article. The principal directions of the stress tensor and strain tensor are generally not coincident, and the values of deformation parameters, Young's modulus and Poisson's ratio, are direction dependent; these two aspects are also discussed in this paper. Whereas this matrix can be used in static numerical analyses for elastic problems, we note that this relationship can also be used as a basis upon which to derive a fully incremental stress-strain relationship for anisotropic granular materials in the plastic state, where the anisotropy is evolving with strain.
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    A fully coupled non-linear dynamic analysis procedure and its verification using centrifuge test results (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 305-325 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The equations governing the dynamic behavior of saturated porous media as well as a finite element spatial discretization of these equations are summarized. A three-parameter time integration scheme called the Hilber-Hughes-Taylor α-method is used together with a predictor/multi-corrector algorithm, instead of the widely used Newmark's method, to integrate the spatially discrete finite element equations. The new time integration scheme possess quadratic accuracy and desirable numerical damping characteristics. The proposed numerical solution and bounding surface plasticity theory to describe the constitutive behaviour of soil have been implemented as the computer code DYSAC2. Predictions made by DYSAC2 code are verified using dynamic centrifuge test results for a clay embankment. Importance of initial state of a soil on its dynamic behaviour is demonstrated.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 355-357 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610180506
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    Boundary element analysis of Biot consolidation in layered elastic soils (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 377-396 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Biot's linear consolidation analysis of three-dimensional fluid saturated layered soils is investigated. The time marching method, uncoupled boundary element method, and successive stiffness method are applied for the numerical modelling of this study. Settlement induced by surface loading and land subsidence due to pumping is studied. The results show that settlement induced by surface loading is mainly influenced by the properties of the soil layer, and that the settlement is larger for soil layers with smaller stiffness and greater thicknesses. The land subsidence induced by pumping is influenced by the properties of the soil layer as well as by the permeability of the pumped layer and the conditions at the top and bottom boundaries. The land subsidence is larger for soil layers with a smaller stiffness, lower permeability of the pumped layer, deeper pumping depth, larger pumping rate and an impervious top surface.
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    A macroscopic elastoplastic constitutive law for multilayered media: Application to reinforced earth material (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 507-518 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper refers to the formulation of a macroconstitutive law for elastoplastic multilayered media, using both thermodynamical approach and homogenization procedure. The latter shows that both the microstress and strain tensors are constant in each constituent. This result permits the formulation of a macroconstitutive law involving the microplastic strains as internal parameters. Both the macrofree energy and dual dissipation potential are computed and used to derive explicit expressions for the macrocompliance tensor, yield surface and hardening rule. Finally, this law is used to analyse the behavior of a reinforced earth material under various loading paths.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 581-584 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610180805
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    Interpretation of cone penetration results in multilayered soils (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 585-599 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A simple approximate analysis is presented for interpretation of cone penetration results when the cone resistance is affected by layering of soils with different stiffnesses. It is argued that the cone resistance senses the presence of a nearby layer elastically, and an approximate elastic analysis is developed to quantify the effect. Good comparisons with calibration chamber experimental results are found.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610181001
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    Zero thickness interface elements - numerical stability and application (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 689-708 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Many methods have been proposed to model joints in rocks or the interface between soil and a structure. Many analysts have reported numerical problems when using zero thickness interface elements while others have presented satisfactory results without comment of such difficulties. The numerical behaviour of zero thickness interface elements is further investigated in this paper. Some simple examples illustrate the application of interface elements to practical situations and highlight the numerical difficulties that may be encountered. Both ill-conditioning of the stiffness matrix and high stress gradients were found to cause numerical instability. Ill-conditioning can be reduced by careful selection of the size of the 2D elements adjacent to the interface. The problem of steep stress gradients is entirely one of inadequate mesh design. Contrary to other reports, this paper shows that the Newton-Cotes integration scheme has no benefit over Gaussian integration.Analyses of a retaining wall using interface elements confirm the analytical values of active and passive earth pressure coefficients which are commonly used in analysis and design of retaining walls.
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    Strain localization analysis by elasto-viscoplastic softening model for frozen sand (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 813-832 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The aim of the present paper is to numerically analyse the behaviour of frozen sand by using a viscoplastic constitutive model with strain softening. A constitutive model has been developed introducing the stress history tensor which is a functional of the stress history, with respect to a generalized time measure. It is shown that Adachi and Oka's model is applicable to the results of triaxial tests on a frozen Toyoura sand at different strain rates. First, the instability of the model is discussed within the framework of bifurcation theory. The model is then implemented into a FEM code to numerically simulate the behaviour under plane strain conditions. From the numerical results, it is revealed that the formation of shear bands is possible and the characteristics of strain localization, such as shear banding, depend on the strain rates.
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    Contaminant leakage from deeply buried cylindrical repositories (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 565-580 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The presence of any leak in a waste repository is going to cause some concern since it may lead to the contamination of the surrounding soil and groundwater. This is an important problem which occurs and recurs, sometimes despite the precautions taken to minimize the possibility of development of any leak. The effects of contaminant leakage in general are not well understood. Thus it is the aim in this paper to develop some semi-analytical solutions of leakage problems occurring in deeply buried cylindrical repositories. In the solution approach, a series of integral transforms is used to simplify the governing equations and solutions are found in the transform space before numerical inversions are applied to obtain the contaminant concentrations in real space and time. To illustrate the application of the technique, results of some leakage cases are presented.
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    Numerical modelling of transient contaminant migration problems in infinite porous fractured media using finite/infinite element technique. Part I: Theory (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 523-541 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The leakage effect in porous fissured media has been considered in a general sense by introducing a new expression of the leakage term in this paper. The double porosity concept is employed and the related expressions are formulated using the upwind finite element approach. Considering the infinite extension of the problem domain, a mapped transient infinite element has been presented to simulate the far field of the infinite medium. Since the mass transfer function of the present mapped transient infinite element is dependent on both space and time variables, the mechanism of transient contaminant migration problems in infinite porous fractured media can be rigorously simulated because the property matrices of the element are evaluated at any time of interest. By comparing the current numerical results with the analytical ones, the accuracy, correctness and effectiveness of the present method have been established. Three different time discretization schemes were examined and it was found that either the central difference or the backward difference approximation is suitable for the upwind finite element simulation of transient contaminant migration problems.
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    A numerical analysis of the foot-floor interaction in long wall workings (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 641-652 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A mathematical and numerical approach for the description of creep and failure of coal around a longwall is given. Two coal strata are considered. They are assumed to be elasto-viscoplastic. The variation in time of the stress and displacement around the excavation, as well as the limit thickness of the upper stratum which would avoid failure was found.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 653-655 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610180906
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    A three-invariant smooth cap model with mixed hardening (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 657-688 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A cap model is presented that uses a multiplicative formulation to define a smooth (continuous derivative) failure surface that includes the third stress invariant. This formulation offers several advantages over previous cap model formulations: elimination of ‘corner’ coding, resulting in a numerical algorithm suitable for vectorization; a three stress invariant implementation that is easily specialized to classical failure surfaces or generalized to represent observed material response; and a framework for easily implementing additional model features such as kinematic hardening as demonstrated.
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    Conference diary (1994)
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    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 809-811 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Unified 3D critical state bounding-surface plasticity model for soils incorporating continuous plastic loading under cyclic paths. Part II: Calibration and simulations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 759-784 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A systematic calibration procedure for the constitutive model gUTS using conventional triaxial data for all but one of the material constants is described. Typical ranges for the constants for clay and sand are specified together with default values. When all default values are adopted, just eight material constants need to be determined (gUTS-lite). A comprehensive series of 49 simulations on clays, silt and sands in loose and dense states under a wide range of monotonic and cyclic stress paths, initial states and drainage conditions provide very satisfactory agreement with experimental results.
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    Masthead (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    Masthead (1994)
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    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    Comparison of calculational approaches for structural deformation in jointed rock (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 327-344 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Results from five different computer models for structural deformation in jointed rock are compared for a problem involving stress-wave loading of a lined circular tunnel in a jointed medium. The computer models include two discrete element codes, The Direct Interacting Block Systems (DIBS) and The Universal Distinct Element Code (UDEC), and three finite element codes, The Finite Element Code for Largely Explicit Calculation (FLEX), The Explicit Calculations of Interacting Bodies Under Rapid Loading Code (EXCALIBUR), and PRONTO. The finite element codes used either slidelines or joint elements to simulate the motion on joints.All codes had some difficulties with a sequence of preliminary problems solved to ‘shake down’ the computer codes. However, most of the shortcomings of each code were readily overcome. Results showed that three codes could obtain similar answers for tunnel closure, stress around the tunnel and slip on the joints.
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    A 2D coupled finite element and boundary element scheme to simulate the elastic behaviour of jointed rocks (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 49-71 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: In this paper a coupled finite and boundary element formulation is developed for the analysis of excavation in jointed rock. The presence of joints in the rock mass has been included implicitly by treating it as an appropriate anisotropic elastic continuum. The boundary element formulation for an anisotropic medium is briefly discussed. Good agreement has been found between numerical and analytical solutions for several example problems, demonstrating the accuracy of the present formulation. Numerical solutions are also presented for the problems of a deep circular tunnel and a basement excavated in a variety of jointed rock masses.
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    A continuum theory of granular media partially saturated with a viscous fluid (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 93-105 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: This paper is concerned with the behaviour of granular media containing voids penetrated by a mixture of viscous liquid and gas (air). It is assumed that, for such materials, the skeleton may be considered as rate-independent and the sensitivity to the applied loading rate may be attributed to the viscosity of the liquid filling the void space. Within the context of geomechanics, such assumptions appear to be relevant to all coarse-grained cohesionless materials, including saturated sands. A mathematical formulation for the description of undrained response is presented. The macroscopic properties are estimated based on volume averaging, which is applied to both stress and strain measures within the heterogeneous constituent medium. Numerical examples are provided illustrating the influence of the viscosity of the liquid on the liquefaction potential of a loose granular assembly.
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    Conference diary (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 141-143 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    URL: http://dx.doi.org/10.1002/nag.1610180208
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    On the indentation of a poroelastic layer (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 161-175 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The paper examines the axisymmetric contact problem related to the indentation of a fluid saturated poroelastic layer by a smooth rigid punch. The layer rests in bonded contact with a rigid impermeable base and the surface of the layer is considered to be either permeable or impermeable. The paper develops the integral equations governing the problem for the generalized case where the pore fluid exhibits compressibility. The numerical results presented in the paper illustrate the influence of the relative layer thickness, drainage conditions and the compressibility of the pore fluid on the degree of consolidation settlement of the indenting punch.
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    Masthead (1994)
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    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
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    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    Masthead (1994)
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    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994) 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
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    Inverse analysis of an embankment on soft clay by extended Bayesian method (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 709-734 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A new type of indirect inverse analysis procedure is proposed to overcome the difficulties the geotechnical inverse analyses are encountering (such as unstability and non-uniqueness of the solutions as well as multicollinearity). These difficulties are eased by combining the objective information (i.e. the observation data) and the subjective information (i.e. the prior information) in an appropriate manner by so-called extended Bayesian method. The method is based on a new view on Bayesian model proposed by Akaike. The problem of model identification in the inverse analysis is also tackled by applying well-known AIC but of the Bayesian version. A case study on an embankment on soft clay is presented to illustrate the effectiveness of the new method. A rather thorough review on the geotechnical inverse analysis is also presented to indicate the necessity of the proposed procedure. An appendix is attached to summarize the statistical background of the new method.
    Additional Material: 9 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610181004
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    Unified 3D critical state bounding-surface plasticity model for soils incorporating continuous plastic loading under cyclic paths. Part I: Constitutive relations (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 735-758 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The unified three-dimensional (3D) critical state bounding-surface plasticity model gUTS enables clays, silts and sands to be treated within a single framework. Furthermore, loose and dense states of a particular soil subjected to a wide range of confinements are viewed as a single material defined by the same set of constants. The model is able to handle both monotonic and complex cyclic paths including those involving a rotation of the principal stress directions. The model incorporates the following features: combined use of radial and deviatoric mapping rules and the use of an apparent normal consolidation line for sands; use of a non-associated flow rule where the ratio of the rates of volumetric plastic strain to deviatoric plastic strain is a function only of the ratio of deviatoric to mean effective stresses and the Lode angle; adoption of a bi-linear critical state line projected onto the plane of the void ratio versus logarithm of mean effective stress; inclusion of a sub-elliptic, or super-elliptic, segment in the plastic dilatancy surface for stress ratios less than critical; use of elliptic segments in the deviatoric planes; movement of the projection centre in the deviatoric mapping region and incorporation of a plastic stiffening effect for cyclic paths which repeatedly load in the same deviatoric direction.
    Additional Material: 7 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610181102
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    Wave-induced soil response in an unsaturated anisotropic seabed of finite thickness (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 785-807 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: An analytical solution for the wave-induced soil response is developed for a seabed of finite thickness subject to a three-dimensional (3-D) wave system produced by two intersecting waves of equal properties. These 3-D exact solutions for the pore pressure and effective stresses, proposed for a non-cohesive soil matrix of finite depth in a homogeneously unsaturated and anisotropic condition, are readily reducible to the limiting two-dimensional cases of progressive and standing waves, for which no explicit solutions are available for finite thickness. The effects of soil isotropy, degree of saturation, seabed thickness and grain size on the wave-induced pore pressure are discussed in detail. The explicit solutions presented in this study for the wave-induced pore pressure and effective stresses should benefit the laboratory experiments and field monitoring programs carried out in soil of finite depth.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610181104
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    A simple hypoplastic constitutive model for sand (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 833-862 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The paper presents a hypoplastic constitutive model for the three-dimensional non-linear stress-strain and dilatant volume change behaviour of sand. The model is developed without recourse to the concept in elastoplasticity theory such as yield surface, plastic potential and decomposition into elastic and plastic parts. Benefited from the non-linear tensorial functions available from the representation theorem the model possesses simple mathematical formulation and contains only four material parameters, which can be easily identified with triaxial compression tests. Comparison of the predictions with the experimental results shows that the model is capable of capturing the salient behaviour of sand under monotonic loading and is applicable to both drained and undrained conditions.
    Additional Material: 18 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610181203
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    Transient response of reservoir-dam-soil systems to earthquakes (1994)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 18 (1994), S. 863-880 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A direct time-domain numerical procedure is proposed to analyse the transient dynamic response of two-dimensional reservoir-dam-soil systems. The reservoir extends to infinity and the dam is supported by an unbounded soil. The structure with either linear or non-linear material properties is modelled by the Finite Element Method (FEM). The soil is assumed to be an elastic, isotropic and homogeneous half-space represented by a boundary condition in the form of generalized impedance determined by the transient Lamb's solution due to a uniformly distributed traction imposed on the free surface, Guan and Novak.1 Moreover, a technique is developed to include the influence of the reservoir on the dam in terms of nodal accelerations along their interface at different time steps. The advantages of the proposed procedure are obvious. For example, it avoids any additional discretization of the boundaries except the soil-dam interface, and the influence matrix of the fluid is obtained explicitly using shape functions defined at the upstream face of the dam without the finite analysis of the reservoir so that it works very efficiently. Numerical results for a system consisting of reservoir, elastic dam and foundation subjected to the San Fernando, 1971 earthquake ground motion are presented.
    Additional Material: 11 Ill.
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    URL: http://dx.doi.org/10.1002/nag.1610181204
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    Microbial biomass turnover and enzyme activities following the application of farmyard manure to field soils with and without previous long-term applications (1993)
    Springer
    Biology and fertility of soils 15 (1993), S. 60-64 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Dehydrogenase activity ; Phosphatase activity ; Turnover ; Farmyard manure ; Soil enzymes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We studied the build-up and turnover of microbial biomass following the addition of farmyard manure to an unmanured soil and to soils from a long-term experiment in which different levels of farmyard manure had been applied for the last 23 years. The application of farmyard manure at 15–90 t ha-1 to previously unmanured soil increased the microbial biomass during the first 3 months of incubation but a gradual decline occurred with further incubation for up to 12 months. Microbial biomass C was positively correlated with soil organic C and ranged from 1.8% to 2.2% of organic C after 12 months of farmyard manure applications. Biomass turnover increased with the application of farmyard manure, ranging from 0.81 to 0.87 year-1 with various levels of manure. Amendment of soils from the long-term manure experiment with various levels of farmyard manure led to a build-up and decline in biomass C as seen in the unmanured soils, but biomass C was higher in all treatments compared to the corresponding unmanured soil treatments. Biomass turnover was greater compared to the unmanured soil treatments and it decreased with increasing levels of farmyard manure. The average soil respiratory activity increased with increasing levels of farmyard manure, but respiratory activity per unit of biomass C decreased with increasing levels of manure. Enzyme activities were greater in long-term manured soils compared to unmanured soils amended with various levels of manure. There was a significant correlation between biomass C and enzyme activities.
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    URL: http://dx.doi.org/10.1007/BF00336290
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    Effects of pine roots on microorganisms, fauna, and nitrogen availability in two soil horizons of a coniferous forest spodosol (1993)
    Springer
    Biology and fertility of soils 15 (1993), S. 113-119 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Microarthropods ; Nematodes ; Rhizosphere ; Disturbance ; Microcosm
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary We investigated the effects of pitch pine seedling roots on extractable N, microbial growth rate, biomass C and N, and nematodes and microarthropods in microcosms with either organic (41% C, 1.14% N) or mineral (0.05% C, 0.01% N) horizon soils of a spondosol. Root quantity was manipulated by varying plant density (0, 1, 2, or 4 seedlings) and rhizosphere soil was separated from non-rhizosphere soil by a 1.2 μm mesh fabric. In the rhizosphere of organic soil horizons, moisture, microbial growth rate, biomass C and N, and extractable N declined as root density was increased, but there was little effect on nematodes or microarthropods. High levels of extractable N remained after 5 months, suggesting that N mineralization was stimulated during the incubation. In the rhizosphere of mineral soil horizons, microbial growth rate, and nematode and microarthropod abundances increased at higher root density, and in the absence of roots faunal abundance approached zero. Faunal activity was concentrated in the rhizosphere compared to non-rhizosphere soil. In organic soil horizons, roots may limit microbial activity by reducing soil moisture and/or N availability. However, in mineral soil horizons, where nutrient levels are very low, root inputs can stimulate microbial growth and faunal abundance by providing important substrates for microbial growth. Our results demonstrate a rhizosphere effect for soil fauna in the mineral soil, and thus extends the rhizosphere concept to components of the soil community other than microbes for forest ecosystems. Although our results need to be verified by field manipulations, we suggest that the effects of pine roots on nutrient cycling processes in coniferous forests can vary with soil nutrient content and, therefore, position in the soil profile.
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    URL: http://dx.doi.org/10.1007/BF00336428
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    Response by soil nematode populations and the soil microbial biomass to a rain episode in the hot, dry Negev Desert (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 188-192 
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    ISSN: 1432-0789
    Keywords: Nematodes ; Microbial biomass ; Rain episode ; Negev Desert ; Diurnal fluctuations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Since the amount, intensity, and frequency of rainfall in desert regions vary strongly over space and time, the response by soil biota to this variability is of great importance. We conducted a study in the Negev desert in order to examine the immediate response by the soil nematode populations and the microbial biomass to varying amounts of water applied in a single pulse. Soil samples from the 0–10-cm depth were collected from areas undergoing four different wetting treatments, comprising 5, 10, 15, and 20 mm of water, and from a non-irrigated control soil. There was a correlation between diurnal variations in nematode populations and the diurnal fluctuations in soil moisture. The greatest abundance of nematodes was found in the soil treated with 20 mm water (970 individuals 100 g-1 dry soil) which was 2, 4, 5, and 14 times larger than that found in the soil treated with 15, 10, 5, and 0 mm of water, respectively. Bacterialfeeding and fungal-feeding nematodes accounted for approximately 95% of the total nematode population found in all treatments. The microbial biomass examined in the current study exhibited an immediate response to the wetting which was greater in soil treated with, 10, 15, and 20 mm of water compared with 0 and 5 mm. However, after 4 days (96 hours) the microbial biomass stabilized again at the basic level of the 0-mm control. However, our results indicated that the major trigger for changes in the nematode populations, and in the microbial biomass, was diurnal fluctuations in soil moisture, since peaks in nematode populations and in the microbial biomass were observed at various times of the day.
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    URL: http://dx.doi.org/10.1007/BF00361406
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    The influence of nitrogen on atrazine and 2,4-dichlorophenoxyacetic acid mineralization in grassland soils (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 179-182 
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    ISSN: 1432-0789
    Keywords: Grassland soils ; Microbial biomass ; Nitrogen fertilization ; Atrazine ; 2,4-D ; Radiometric techniques ; Herbicide mineralization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The influence of fertilizer N on the mineralization of atrazine [2-chloro-4(ethylamino)-6(isopropylamino)-s-triazine] and 2,4-D (2,4-dichlorophenoxyacetic acid) in soils was assessed in microcosms using radiometric techniques. N equivalent to 0, 250, and 500 kg N as NH4NO3 ha-1 was added to three grassland soils. Compared to the control, the 250- and 500-kg treatments suppressed mineralization of atrazine by 75 and 54%, respectively, and inhibited mineralization of 2,4-D by 89 and 30%, respectively. Active fungal biomass responded to the N treatments in an opposite manner to herbicide mineralization. Compared to the control, the 250- and 500-kg treatments increased the active fungal biomass by more than 300 and 30%, respectively. These results agree with other observations that N can suppress the decomposition of resistant compounds but stimulate the primary growth of fungi. The degree of suppression was not related to the amount of N added nor to the inherent soil N levels before treatment. The interaction between the N additions and the active fungal biomass in affecting herbicide mineralization suggests that N may alter microbial processes and their use of C sources and thus influence rates of herbicide degradation in the field.
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    Influence of pH, dispersion methods, and different compounds on adenosine triphosphate recovery from soil (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 238-242 
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    ISSN: 1432-0789
    Keywords: Soil ATP extraction ; Soil ATP adsorption ; Microbial biomass ; Ballottini mill ; Extracting chemicals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We studied the recovery of ATP from soil. A soil-water suspension was prepared by two different methods (simple stirring or ballottini mill treatment) at different pH levels and in the presence of different chemicals [Na2SO4, Na3PO4, Na5P3O10, adenosine, ethylenediaminetetra-acetic acid (EDTA), TRIS]. The ATP recovery was evaluated by adding [3H]-8′ ATP to the solution and comparing the values obtained by radioactivity measurements with those obtained by an enzymatic assay. Strongly acidic (pH lower than 1.0) or alkaline (pH 10.0) extractions yielded the best ATP recoveries compared with intermediate pH values. At pH 10.0, the addition of Na3PO4 or Na5P3O10 gave a high level of ATP recovery, 68 and 96%, respectively. No ATP hydrolysis occurred under alkaline extraction conditions. Under acidic extraction conditions, the addition of adenosine, EDTA, Na2SO4, or Na5P3O10 improved ATP recovery but it was never higher than 34%. The results were discussed in terms of the effects of different physical and chemical conditions on cell disruption, ATP stability, ATP interactions with soil components, and ATP solubilization.
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    Effect of cattle slurry in grassland on microbial biomass and on activities of various enzymes (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 249-254 
    Details
    ISSN: 1432-0789
    Keywords: Microbial biomass ; Soil enzymes ; Nitrification ; Cattle slurry ; Grassland soils
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the long-term effects of cattle slurry, applied at high rates, on microbial biomass, respiration, the microbial quotient (qCO2) and various soil enzyme activities. In March, June, July, and October 1991, slurry-amended grassland soils (0–10 cm) contained significantly higher levels of microbial biomass, N mineralization and enzyme activities involved in N, P, and C cycling. With microbial biomass as the relative value, the results revealed that the slurry treatment influenced enzyme production by the microbial biomass. High levels of urease activity were the result not only of a larger microbial biomass, but also of higher levels of enzmye production by this microbial biomass. The ratio of alkaline phosphatase and xylanase to microbial biomass was nearly constant in the different treatments. The metabolic quotient (qCO2) declined with increased levels of slurry application. Therefore it appears that microorganisms in slurry-amended soils require less C and energy if there is no competition for nutrients. The results of this study suggest that urease activity, nitrification, and respiration (metabolic quotient) can be used as indicators of environmental stress, produced by heavy applications of cattle slurry.
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    Effect of residue placement and chemical fertilizer on soil microbial biomass under tropical dryland cultivation (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 275-281 
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    ISSN: 1432-0789
    Keywords: Nutrient dynamics ; Dryland agriculture ; Reduced tillage ; Microbial biomass ; Straw application ; Fertilization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Four treatments (control, chemical fertilizer, wheat straw, and wheat straw+fertilizer) were established on the dryland experimental farm of the Institute of Agricultural Sciences, Banaras Hindu University. Organic in C in the different treatments ranged from 0.69 to 0.93%, total N from 0.08 to 0.11%, and total P from 0.018 to 0.021. The application of straw significantly increased the soil water-holding capacity. The maximum effect on the microbial biomass was realized with the straw+fertilizer treatment, followed by straw and then by the fertilizer treatment. During the study microbial biomass C ranged from 144 to 491 μg g-1 dry soil, biomass N from 14.6 to 50.1 μg g-1, and biomass P from 7.2 to 17.6 μg g-1 soil. Microbial biomass C, N and P represented 3.2–4.6% of total C, 2.6–3.8% of total N, and 5.8–8.2% of total P in the soil, respectively, in all cases the highest proportion occurred in the straw+fertilizer treatment and the lowest in the control. Microbial biomass C, N, and P were positively correlated with each other. Microbial biomass C and N increased by 77% in straw+fertilizer-treated plots relative to the control. The increase in microbial biomass P in the straw+fertilizer treatment over the control was 81%. The increase in the microbial biomass is expected to enhance nutrient availability in the soil, as the microbial biomass acts both as a sink and a source of plant nutrients.
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    The effect of tropical forest conversion on soil microbial biomass (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 302-304 
    Details
    ISSN: 1432-0789
    Keywords: Tropical forest soil ; Savanna ; Microbial biomass ; Basal respiration ; Metabolic quotient ; Soil organic carbon
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We investigated the effects of converting forest to savanna and plough land on the microbial biomass in tropical soils of India. Conversion of the forest led to a significant reduction in soil organic C (40–46%), total N (47–53%), and microbial biomass C (52–58%) in the savanna and the plough land. Among forest, savanna, and plough land, basal soil respiration was maximum in the forest, but the microbial metabolic quotient (qCO2 was estimated to be at a minimum in the forest and at a maximum in the plough land.
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    Effects of vegetation regime on denitrification potential in two tropical volcanic soils (1993)
    Springer
    Biology and fertility of soils 16 (1993), S. 157-162 
    Details
    ISSN: 1432-0789
    Keywords: Denitrification ; Soil respiration ; Nitrous oxide ; Tropical volcanic soils ; Microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Effects of vegetation and nutrient availability on potentail denitrification rates were studied in two volcanic, alluvial-terrace soils in lowland Costa Rica that differ greatly in weathering stage and thus in availability of P and base cations. Potential denitrification rates were significantly higher in plots where vegetation had been left undisturbed than in plots where all vegetation had been removed continuously, and were higher on the less fertile of the two soils. The potential denitrification rates were correlated strongly with respiration rates, levels of mineralizable N, microbial biomass, and moisture content, and moderately well with concentrations of extractable NH inf4 sup+ , Kjeldahl N, and total C. In all plots, denitrification rates were stimulated by the removal of O2 and by the addition of glucose but not by the addition of water or NO inf3 sup- .
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    Thermomechanical effects on adsorbed water in clays around a heat source (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 175-196 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Numerical results of the simulations of the saturated clay response to a line heat source with a constant power output are presented and compared to the analytical solutions. Mixture theory of two interacting thermoelastic constituents is employed for the modelling. In this theory, mass transfer between the adsorbed water and bulk water is included to simulate the degeneration of adsorbed water into bulk water occurring at elevated temperatures. A finite difference method with non-uniform mesh is adopted to determine both the near- and far-field behaviour. The degeneration of adsorbed water into bulk water is more pronounced close to the heat source. This may produce a lower excess pore water pressure, a higher permeability increase, and accelerate the water flow in the vicinity of the heat source.
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    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993) 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170101
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    Green's functions for a fully coupled thermoporoelastic material (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 139-163 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The Green's functions for a set of fully coupled linear equations governing thermal consolidation of a homogeneous isotropic material are presented. The Green's functions are evaluated for one, two and three spatial dimensions, and in the Laplace and real-time domains. The Green's functions are employed in a boundary integral analysis of a simple problem to demonstrate the influence of full coupling on the field quantities.
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    Letter to the Editor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 205-207 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Additional Material: 2 Ill.
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    Conference diary (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 213-215 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170308
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    Masthead (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993) 
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    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170401
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    Effect of sand lenses on groundwater flow and contaminant migration (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 217-241 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The effect of homogeneous sand lenses on the groundwater flow in an otherwise homogeneous clayey deposit is examined by performing Monte Carlo simulations using a finite element flow model. In the simulations, the locations of the sand lenses are assumed to be mutually independent. The paper examines the effect on the flow field in a clayey deposit of (a) different percentages of sand lenses, (b) different hydraulic conductivities of the sand lenses, (c) different average sand lens sizes, (d) non-uniformity of the sizes of the sand lenses, and (e) localization of the sand lenses. The effect of these non-uniform flow fields on contaminant migration is then examined using a finite element contaminant transport model. For the range of cases considered it is shown that: the volume of sand lenses present has a greater influence than the shape, size, location and hydraulic conductivity of the sand lenses; simplified calculations performed using the geometric and harmonic means of hydraulic conductivity bracket the behaviour evident from more complex analyses; and the maximum impact on an aquifer separated from a waste disposal facility by a deposit containing sand lenses can be modelled to sufficient accuracy, using quite simple flow and contaminant transport models.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170402
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  • 93
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    The axial loading of a rigid circular anchor plate embedded in an elastic half-space (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 343-353 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: The present paper examines the axisymmetric problem related to the loading of a rigid circular anchor plate which is embedded in bonded contact with an isotropic elastic half-space. A Hankel transform development of the governing equations is used to reduce the associated mixed boundary value problem to a set of coupled Fredholm integral equations of the second kind. These equatons are solved in a numerical fashion to generate results of engineering interest. In particular, the results indicate the influence of the depth of embedment on the axial stiffness of the rigid anchor plate.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170505
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  • 94
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    Announcement (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 355-356 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170506
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  • 95
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    Boundary element analysis of contaminant transport in fractured porous media (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 471-492 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A two-dimensional boundary integral method to analyse the flow of contaminant in fractured media having a two- or three-dimensional orthogonal fracture network is presented. The method assumes that the fractures provide the paths of least resistance for transport of contaminants while the matrix, because of its low permeability, acts as ‘storage blocks’ into which the contaminant diffuses. Laplace transform is used to eliminate the time variable in the governing equation in order to facilitate the formulation of a boundary integral equation in the Laplace transform space. Conventional boundary element techniques are applied to solve for the contaminant concentrations at specified locations in the spatial domain. The concentration in the time domain is then obtained by using an efficient inversion technique developed by Talbot. The method is able to analyse the behaviour of waste repositories which have diminishing concentration due to the mass transport of the contaminant into the surrounding fractured media.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170704
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  • 96
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    Influence of relative density and stress level on the bearing capacity of sands (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 871-890 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A finite element approach is presented to determine the bearing capacity of shallow footings on silica sand deposits. The approach can take into account the effects of relative density and stress level on the shear strength of granular soil and is applicable to a fairly large effective stress range. The strength of sand is characterized by a non-linear Mohr-Coulomb criterion which depends on maximum and critical friction angles, widely used parameters in engineering practice. The results of analysis indicate that this approach yields reliable predictions of bearing capacity and, in particular, it can model the volumetric behaviour of the soil at failure.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610171204
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  • 97
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    An approximate analysis procedure for piled raft foundations (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 849-869 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: A piled raft foundation comprises both piles and a pile cap that itself transmits load directly to the ground. The aim of such a foundation is to reduce the number of piles compared with a more conventional piled foundation where the bearing effect of the pile cap, or raft, is ignored. This paper describes a ‘hybrid’ approach for the analysis of piled raft foundations, based on a load transfer treatment of individual piles, together with elastic interaction between different piles and with the raft. The numerical analysis is used to evaluate a simple approximate method of estimating the overall response of the foundation from the response of the component parts. The method leads to estimates of the overall foundation stiffness, the proportion of load carried by the pile group and the raft, and an initial assessment of differential settlements. Parametric studies are presented showing the effect of factors such as raft stiffness and pile spacing, length and stiffness, and a worked example is included demonstrating the accuracy of the approximate design approach.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610171203
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  • 98
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    Negative skin friction on single piles in a layered half-space (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 625-645 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Settlement of the surrounding soil due to surcharge placement may give rise to negative skin friction developed in piles. In this paper, a simple discrete element approach using subgrade reaction method is proposed to analyse negative skin friction on single piles. The pile is embedded in a two-layer soil where the upper soil layer undergoes consolidation while the lower soil layer acts as a stiffer bearing stratum. Two different and uncoupled deformation modes, one at the pile shaft and the other at the pile toe have been assumed in the determination of the soil stiffness. The effects of a compressible bearing stratum and embedment length of the pile in the bearing stratum are considered in the analysis. This simple approach is verified by comparison with rigorous methods of modelling the soil as an elastic continuum. Three reported case histories are analysed and the computed results are shown to be in reasonable agreement with the field measurements.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170903
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  • 99
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    Letter to the Editor (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 669-674 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610170906
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  • 100
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    Numerical solution for the dilation of a fluid-saturated porous elastic sphere due to a point source of fluid at the centre of the sphere (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 17 (1993), S. 699-714 
    Details
    ISSN: 0363-9061
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Architecture, Civil Engineering, Surveying , Geosciences
    Notes: Mathematical modelling of the ascent of free fluid through relatively strong rock, deep in the Earth's mantle, presents a challenge in geomechanics. Here the medium is considered as fluid-saturated, porous, elastic and bounded, and the fluid enters at a point source. An explicit finite difference method is developed for the numerical solution to the problem of the dilatation of a fluid-saturated porous elastic sphere due to a point fluid source of constant strength at the centre of the sphere. A cubic spline interpolant is used to evaluate a definite integral which occurs in the boundary condition for the pore fluid pressure at the surface of the sphere. The numerical solutions for the dilatation and pore fluid pressure are compared with analytical solutions and the absolute and relative errors of the numerical solutions are calculated. When the fluid source is switched on, the pore fluid pressure starts to decrease, reaches a minimum value and then steadily increases. The initial time rate of decrease of the pore fluid pressure is independent of the radial distance from the source. It decreases as the radius of the sphere increases and vanishes for a point fluid source in an infinite porous elastic medium.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nag.1610171003
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