The purpose of this study was to establish the influences of physico-chemical properties of soil particles on the hydraulic conductivity of partially saturated decomposed granite soil. The influences of water content during permeation and specific surface area of soil particles on the hydraulic conductivity were examined in detail. Water content determinations were made by a gamma ray radiation method, and specific surface area was calculated from the pore size integral curve obtained using a mercury pressure porosimeter.It was concluded that specific surface area can be correlated with specific gravity, apparent specific gravity, and the 50% size of the graduation curve. The water content measured during permeability tests can be estimated immediately by count ratio of gamma ray radiation. Hydraulic conductivity can be related to volumetric water content and specific surface area, both of which have a close relation to the physical properties of soil particles.

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In this paper the problem of liquefaction of sand under either monotonic or cyclic loading is tackled from the point of view of Continuum Mechanics. It is shown that a suitable constitutive model may explain, in a phenomenological sense, the generation of pore pressure in an undrained test either when the load is monotonically increased to failure or when sand is cyclically sheared at constant stress or strain amplitudes. It is demonstrated that in the former case liquefaction of loose samples may be described if a convenient set of constitutive parameters is chosen. It is also shown that liquefaction under cyclic loading may occur even for very dense sands, and that the essential features revealed by experiments, such as progressive pore pressure build-up accompanied by small shear strains followed by a sudden pore pressure increase with large strains, are correctly modelled by the theory.The constitutive model employed is a combination of a classical elastoplastic constitutive law, which proved to be successful in modelling the behaviour of sand under monotonic loading, and of a law allowing for hysteresis, which applies to loading processes within the yield locus, especially conceived to interpret the behaviour of soils under cyclic loading.

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The bearing capacities of slopes loaded on top surfaces were calculated by using the upper bound theorem. Through the comparison of the results with bearing capacities obtained by conventional circular arc methods and by Kotter's stress characteristics equations, it was concluded that the upper bound solution was useful from the engineering point of view because of simplicity of the method.Model tests using Kanto loam were conducted to check the validity of the upper bound calculation. It was shown that the agreement between the theory and the observation was generally good, although the theory yielded slightly higher values than those observed. The side friction in model tests and the difference in stress state between the tests and the computation were considered to be possible causes for the discrepancy.The lower bound analysis was also attempted, which showed that the upper bound solutions were good approximations of exact solutions for bearing capacities of loaded slopes.All the computed results were produced in charts for the convenience of design engineers.

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In order to clarify the influence of inherent anisotropy on the deformation-strength behaviours for an assembly consisting of spherical particles, isotropic compression tests and radial shear stress tests were performed on cubical specimens consisting of glass beads under the condition of independent stress control. In all the tests, the direction of specimen deposition was identical with that of gravity. The test results are summarized as follows. For random packing of spheres deposited by free falling under the action of gravity, an inherent anisotropy was considered to have been caused by the requirements of sphere-stabilities. In the direction of specimen deposition, the specimens showed a compressibility which was lower than that in the direction perpendicular to that of specimen deposition. The deformation-strength behaviours were consequently affected by the relation between the direction of specimen deposition and that of the radial shear stress path.

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Although vertical oscillations may have a profound effect on the seismic stability and deformability of embankment dams, they have received so far little, if any, attention. Filling this gap, the paper develops a simple but realistic two-dimensional method for evaluating the dynamic characteristics and analyzing the seismic behaviour of earth and rockfill dams oscillating in the vertical direction. Shear and dilatational deformations are considered, the dependence of soil stiffness on confining pressure is rationally modeled and the effect of canyon geometry is approximately treated. Numerical results are portrayed in the form of dimensionless graphs of natural frequencies, modal displacement shapes and modal participation factors as functions of characteristic geometric and material parameters. To demonstrate the capability of the developed model to successfully predict the field performance of actual dams, three case studies are presented involving two earth and one rockfill dam from three seismically active countries. Reasonably good agreement is obtained between computed and observed (during earthquake shaking) natural frequencies and vertical crest accelerations.

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Although the vane shear test has become a widely used site investigation method for saturated soft clays, its shear mechanism is very complicated and consequently the significance of the resulting vane strength is not necessarily clarified.In this paper, the shear mechanism of vane test in soft clays is investigated, mainly focussing the stress states on the vertical shear plane. Two types of laboratory vane tests are carried out for the normally K₀-consolidated clays, involving total stress and pore water pressure measurements around shear plane. Also, finite element analysis of vane test is carried out, using a technique of multi-dimensional elasto-plastic consolidation analysis developed by the authors elsewhere.Based on both the experimental and analytical results, some important implications for the vane shear mechanism are shown through considerations of stress distributions and stress path behaviors.

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This paper compares the theories of finite strain consolidation developed by Gibson, England and Hussey (1967) and Mikasa (1963). It is shown that these theories, though independently developed are quite similar. The only difference is that the theory developed by Mikasa inherently assumes a process of rapid sedimentation in which a layer is instanteneously formed at a constant initial void ratio, while the Gibson-England-Hussey theory is unrestricted with regard to its initial conditions.

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A set of piezometers was embedded in sand deposits on a reclaimed island in Tokyo Bay and a seismograph was placed on the ground surface nearby in order to monitor simultaneously in-situ pore water pressures and horizontal accelerations during earthquakes. During the September 25, 1980 earthquake, the instruments registered increases in pore water pressures corresponding to 19% and 16% of the effective overburden pressure at depths of 6.0 m and 14.0 m, respectively. At the same time, a maximum horizontal acceleration of 95 gal was registered at the ground surface. Laboratory cyclic triaxial tests had been performed on undisturbed soil specimens obtained from this site using a large diameter sampler. Based on the laboratory test data, an estimate was made of the pore water pressures that might be produced in the deposit by seismic shaking of a maximum acceleration of 95 gal. The estimated values of pore water pressure were shown to be in good agreement with the pore water pressures registered during the earthquake.

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A complete set of bearing capacity factor for rectangular footings on clays of undrained shear strength (φ=0) increasing linearly with depth was compiled by combining the exact plasticity solution for continuous footings and the slip circle solution for rectangular footings. Effect of increasing strength with depth was expressed in term of the ratio kB/c₀, where k is the rate of increase in strength with depth, c₀ is the strength at the clay surface and B is footing width. It is examined that the value of kB/c₀ likely to be encountered in practice is within the range from 0.2 to 30.As compared with results of the present analysis, three other kinds of bearing capacity formulae proposed for the case of strength increasing with depth, were found to overestimate the bearing capacity. The maximum extent of overestimation expected in practical problem is almost 300%.A set of approximate expressions for bearing capacity factor was proposed for convenience of practical use, which is function of the ratio kB/c₀ and the footing shape B/L. The maximum extent of underestimation by these approximate expressions is 5%.

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A variational method is developed to analytically study the interaction between a circular raft of finite flexibility and a cross-anisotropic elastic soil deposit of infinite extent. The raft rests smoothly on the soil surface and undergoes flexural deformations under the action of uniformly or parabolically distributed axisymmetric external loads and the ensuing soil reactions. Soil anisotropy is treated rigorously and particular emphasis is accorded to the sensitivity of total and differential undrained raft settlements on assumed realistic values of the anisotropic soil parameters.

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