A new look is offered on the energy based stress dilatancy relation in Cam-clay model (Roscoe et al., 1963). In the present study, the volume change due to dilatancy is regarded as the volume change in the void. From this view point, the hypotheses made in deriving the stress dilatancy relation in Cam-clay model will be replaced by four hypotheses as follows; (1) the void consists of contractive and dilative voids, (2) the increment of the volumetric strain in the contractive void is proportional to the increment of the plastic deviator strain of soil through the constant M, (3) the energy dissipated by the void skeleton of the dilative void is none, and (4) the tangential stiffness of soil is continuous. The four hypotheses make it possible to uncover a greater potential in Cam-clay model. In particular, it is suggested that the phase transformation line, which divides the stress space into dilative and contractive zones, should be distinguished from the critical state line.

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The present study discusses the cause of ground heave of an inherently non-swelling, kaolinite-rich red soil (from Bangalore, India) due to prolonged spillage of concentrated (40%, weight/weight solution) caustic soda (sodium hydroxide) solution into the sub-soil through cracked drains in an industrial establishment. The heave of the foundation soil caused considerable distress to the industrial building. The proposed remedial measures to chemically stabilize the contaminated foundation soil against future caustic soda solution spillage are also considered. The observed heave of the undisturbed soil sample in the laboratory oedometer test on permeation of 40% caustic soda solution and the significantly reduced pH of the outflowing caustic soda solution (pH=9.35), suggested that certain chemical reactions occur during the passage of the strong alkali solution through the residual soil that is responsible for the ground heave. It is considered that loss of the cementitious iron oxide coatings coupled with the negative charge imparted to the soil particles by the passage of the caustic soda solution, disperse the soil particles that manifests as ground heave. Treatment of the contaminated ground with 5% ferric chloride solution and simultaneously taking measures to minimize caustic soda solution spillage should stabilize the foundation soil against heave from caustic soda attack for several years.

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The layered clay-sand scheme of land reclamation involves the formation of thin sand seams sandwiched in between hydraulically placed marine clays to provide shorter drainage paths for the rapid consolidation of the clay layers during surcharge application. In a situation of scarce and expensive sand supply, it is desirable to minimize the losses of sand through penetration into the very soft clay slurry during the process of forming the horizontal sand seams. This study provides some insights as to the nature of sand penetration into a clay slurry through a jute interlayer. The factors that affect the efficacy of the jute layer in minimizing sand losses into a clay slurry are the height of drop of the sand through still water before hitting the jute interlayer, the intensity of sand spreading, the relative sizes of sand particles to the opening size of the jute fabric, and the clay slurry strength. Experiments are conducted to examine the effects of each of these factors, and the results are verified by gamma-ray density profiling of the clay column before and after sand spreading. Results indicate that the key factors that control sand penetration are the relative sizes of sand particles to jute opening, the intensity of spreading, and the slurry strength.

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The results of a series of plane strain model loading tests of footing on both reinforced and unreinforced sand slope made of a fine quartz-rich sand, Toyoura sand, performed under well-controlled loading conditions are described. It is shown that the bearing capacity of footing can be increased very efficiently by introducing stiff reinforcing strips into the vicinity of active wedge which occurs in the corresponding unreinforced slope. It is also shown that both the bearing capacity characteristics and the failure patterns of reinforced slopes largely depend on the arrangement of the reinforcement members. The failure pattern of the model slopes are classified into four types. The subsequent stability analyses by using various limit equilibrium methods will be presented in the companion paper, which will appear in the near future.

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A centrifugal model study into the influence of pipe diameter, depth of burial and backfill density on the resistance to uplift of pipes in sand is reported. No significant differences between the behaviour of buried pipes and that of strip anchors is found, justifying the application of anchor uplift theory to buried pipeline behaviour. Several anchor-based theories overestimate the stability of the model pipes tested, although predictions from the theories of Rowe and Davis (1982), Vermeer and Sutjiadi (1985) and Vesic (1971) yield reasonable agreement for models in dense sand, while the simple Vertical Slip Surface Model is alone in providing sensible predictions for pipes in loose sand. The influence of pipe surface roughness, although significant for pipes at shallow depth in dense sand, is minimal at deeper embedments.

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Two series of cyclic loading tests have been carried out on model pile groups jacked into reconstituted calcareous sand beds which were consolidated under different overburden pressures. The first series studied the effects of displacement-controlled cyclic loading on the reduction of skin friction of a model pile group. The results of these tests have shown that this reduction (or "degradation") increases with increasing cyclic displacement and number of cycles. There is only a small effect of the number of piles in the group on reduction of skin friction. The second series of tests studied the effects of uniform cyclic load and non-uniform cyclic "storm" loading tests on the accumulation of permanent displacement of the model pile groups. The results of uniform cyclic loading tests have been summarized in a stability diagram for the pile group in which the influence of cyclic loading on the group capacity can be seen. The results of non-uniform cyclic loading tests have shown the effects of accumulated displacement of the capacity of the groups. The accumulated displacement of a pile group in load-controlled cyclic tests was found to be similar to that of a single pile, with increases in displacement caused by increasing load level being more significant than increases arising from increasing numbers of cycles. There was only a small influence of the number of piles on pile capacity and group settlement for both uniform and non-uniform cyclic loadings. A modified form of boundary element analysis was used to predict the cyclic behaviour of a pile group using input parameters derived from the experimental results for a single pile. Comparisons between the measured and predicted results have shown reasonable agreement.

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Wave equation analysis and dynamic pile testing have been generally accepted by the engineering profession as effective techniques for construction control of driven piles. The accuracy of wave equation analysis, however, is dependent upon the assumed hammer performance and the correct input of dynamic soil-pile interaction model parameters. A host of proprietary numerical simulation programs have been developed to facilitate the calculation of pile capacity and pertinent soil-pile interaction model parameters based on the measured dynamic signals (force and velocity wave forms measured at a point near the pile top) during each hammer blow (usually at the end of initial driving or the beginning of re-strike). The numerical simulation techniques involve the adjustment of the model parameters based on the matching of the calculated signal with a reference signal. Either dynamic force or kinetic velocity is imposed at the top as a stimulus, while the other signal is used as a reference for matching purpose. In this paper, a new numerical simulation algorithm, utilizing both force and velocity as the given boundary stimuli, has been developed. The proposed algorithm differs from the existing numerical programs mainly in that it is cast in a system in which the signal matching process is performed at several points along the pile shaft. In this way, the soil-pile interaction model parameters can be more accurately determined. Furthermore, the proposed algorithm can determine the shaft resistance and toe resistance separately, thus helping the determination of the uplift capacity of driven piles.

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This paper extends a generalized slope stability analysis method to include pseudo-static forces. Formulation and the subsequent numerical procedure of the extended generalized seismic slope stability analysis are presented. Comparison with a closed form approach indicates that the generalized method yields the same safety factor as the closed form approach. This can serve as a partial verification of the accuracy of the numerical procedures. Comparison with other rigorous limit equilibrium methods of seismic slope stability demonstrates that the presented method yields the smallest factor of safety.

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This note presents a comparative study of geosynthetic reinforced slope analyses. The comparison is between predictions of a finite element (FE) method and a limit equilibrium (LE) method. The comparisons are limited to the potential failure surface and the maximum tensile force developed in the geosynthetic reinforcement layers. These two items signify the design output in the LE analysis of geosynthetic reinforced slopes. The agreement between EE and LE methods is found to be reasonably good in terms of both location of critical slip surfaces and required strength of reinforcement.

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For the purpose of making reproducible and homogeneous clayey samples, a new method using artificial sedimentation from a diluted soil-water mixture is proposed. The quality of the samples made from the mixtures with widely varying water content was first investigated for sample homogeneity. Then the mechanical characteristics of the samples were investigated for one-dimensional consolidation and undrained triaxial compression tests. The results showed the following : (1) The high degree of homogeneity can successfully be obtained so long as the water content of the dilute mixture is within a certain range, (2) The compressibility and the permeability strongly depend on the mixture's water content, (3) The triaxial shear behaviour hardly depends on the mixture's water content except for when it is as low as the mixture is in a plastic state.

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Laboratory instrumentation has been developed for sensitive measurement of local lateral-strain of soil specimens. It incorporates a non-contact type of transducer (proximity transducer) whereby lateral deformation of rectangular and circular specimens can be measured in a direct manner at some positions over the central portions, which are relatively free from end restraints. The working principle is described, together with the accuracy and sources of error involved in the measurement. It has been demonstrated in some pilot tests (i.e., drained monotonic loading tests in plane strain compression and a drained cyclic triaxial test) performed on silver Leighton Buzzard and Toyoura sands, that full instrumentation for the local strain measurements, coupled with a previously developed device for the local axial-strain measurement, permitted a continuous examination into the shear-strain-level dependent Young's modulus and Poisson's ratio over a wide range of the pre-failure strain in the orders between 0.0001% and 10%. The scope of the pre-failure strain included the examinations of both the elastic response at extremely small strains less than about 0.002% and the peak strength of a single specimen. It was found that the Poisson's ratio with the shear strain being less than about 0.05% remained more or less constant at around 0.22 and 0.15 for sliver Leighton Buzzard and Toyoura sands, which comprize round and angular to sub-angular grains, respectively. Furthermore, in a broad sense, Rowe's stress-dilatancy relation was found to be valid over the whole range of the pre-failure strain examined, and it was scarcely influenced by the history of over-consolidation at small strains.

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The effects of partial drainage and construction settlement on stability analysis of embankment on soft ground have been investigated by analyzing a built to failure embankment on Muar clay deposit, Malaysian. Although for design, ignoring the partial drainage and construction settlement effects in stability analysis is on safe side, to understand the failure mechanism and to back-analyze the mobilized strength of soft ground at failure, these effects need to be considered. For the embankment analyzed, undrained strength increase and settlement of the ground during construction can cause a increase of factor of safety by about 0.2, or each of the effect by 0.1. The contour of shear stress level (shear stress/shear strength) of the soft ground has been analyzed from finite element analysis results. It has been illustrated that the contour of shear stress level of soft ground can indicate the stability condition of the embankment. At the embankment failure, a large area beneath the embankment and around the embankment toe, the shear stress level is 1.0. However, finite element analysis yields a poor simulation of the foundation deformation ratio (horizontal/vertical).

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