In recent years, strong random earthquake motions have become a matter of great interest among earthquake engineers concerned with the design earthquake of important civil engineering structures such as fill dams. The influence of a strong random earthquake on fill dams is characterized by large accelerations (body forces) in both vertical and horizontal directions.The following four kinds of experiments are conducted in order to investigate the dynamic strength and deformation characteristics of rockfill material : (1) static shear tests; (2) static shear tests with vertical vibration; (3) dynamic shear tests and (4) dynamic shear tests with vertical vibration.The following results are obtained;(1) The body force affects significantly the dynamic deformation behaviours, but only slightly the static deformation and strength.(2) If the ultimate dynamic strength is defined as the maximum shear stress by which the specimen fails in the same way by the static shear stress, the ultimate dynamic strength of a dense rockfill material becomes larger than the static strength in a range of lower sustained stress.(3) The rockfill material becomes unstable with a disturbed grain structure and a large deformation when it is subjected to the dynamic loads exceeding the yield stress ratio, (τ_s/σ_n)_y.Thus, the yield stress ratio becomes an important criterion for the dynamic stability of earth-structures, and the yield stress ratio can be obtained from the static shear test.

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A simple representation of the dynamic lateral load-deflection relationship of a pile is presented for both pile-head and seismic excitation conditions. The lateral load-deflection relationship of a pile is represented by the soil reaction coefficient that is the ratio between a unit soil reaction on a pile and the product of soil modulus and pile displacement relative to the free field. As the soil reaction coefficient varies significantly along the pile even in a homogeneous soil, an averaging procedure is presented to determine an equivalent soil reaction coefficient that is constant with depth. The average soil reaction coefficients, δ^^∼, for homogeneous soil profiles are affected by the loading condition, pile flexibility factor, and pile slenderness ratio. The magnitudes of these influences are quantified.This averaging procedure can also be applied to heterogeneous layered soil profiles if a weighted soil modulus is used. The concept of the average soil reaction coefficient is extended to develop a procedure to compute the dynamic lateral load-deflection relations of piles when the stress-strain response of the soil is nonlinear and degrades due to pore pressure increases with cyclic loading.

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Five erth fills for preloading were constructed on an alluvial marine clay under factor of safety of about 1.0. One erth fill failed and two must have been on the position of failure. First, undrained strength characteristics of the clay at the proposed site are described and discussed as well as the procedure for determining the undrained strength for practical use. Settlement characteristics observed in the field for each earth fill are then reported. Stability analysis for actually constructed earth fills are shown, in which anisotropy in undrained strength and effect of strain rate on undrained strength were considered. The results showed excellent agreement with the field behaviour of each fill and strongly demonstrated that the undrained strength of the clay at the proposed site should be evaluated from consolidated undrained strength tests in which the specimens from undisturbed samples are reconsolidated at the same stresses they carried in the field.

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This paper intends to give theoretical bases for observational settlement prediction methods which use autoregressive equations. The master differential equation derived is demonstrated to be effective even for a multilayered soil system under gradual load application. The technique for parameter identification of higher order autoregressive equations is also provided and numerical simulations show high applicability of the proposed method.

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The paper discusses the geotechnical investigations planned and carried out for a cement factory in boulder deposit. A cement factory normally has very typical structures, e.g. heavily loaded structures as cement silo, tall structures as preheater tower. In addition to these, machine foundations are also required as for crusher and rotary kiln. Keeping in view the nature of the loads, type of structures and the soil strata special geotechnical testing program was planned. The various in-situ tests included (i) field density tests (ii) shear strength tests, (iii) cyclic vertical plate load tests, (iv) horizontal plate load tests, (v) passive earth pressure tests and (vi) block resonance tests. Also, the samples brought from the field were tested in the laboratory for classification purposes. Describing briefly the test procedure, the data obtained from various tests have been interpreted to estimate various parameters used for design of foundations. Based on test data suitable values of angle of internal friction, allowable soil pressure, horizontal subgrade modulus and dynamic soil constants have been recommended for foundation design.

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The Paper describes a method for estimating the one-dimensional consolidation of an aged clay. First, a mathematical model of consolidation is developed by taking account of the properties of aged clays such as preconsolidation and secondary compression effects, and the numerical solutions are presented for some particular cases. By comparison with published experimental results, it is demonstrated that the theory can explain extensively the consolidation characteristics of aged clays. Successively, the determination of the index properties of soil which appear in the theory is considered. The applicability of the theory to practical problems is inferred by comparing with results of model tests in laboratory. Consequently, it is found that the estimate of consolidation by means of the proposed method is fairly surpassing.

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Several methods to evaluate cyclic undrained strengths of sandy soils from standard penetration resistances (N-values) are reviewed and compared. It is shown that some empirical equations which do not take account of the effects of grain size on N-values can be rather conservative for fine or silty sands. When the effects of grain size on N-values are adequately taken into account, strengths estimated from N-values are very close to the measured strengths of undisturbed samples. A simplified procedures for evaluating liquefaction potential of an element is proposed. An index showing integrated liquefaction potential of a deposit is also proposed and examined by a liquefaction case study.

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To investigate the strength characteristics of soft rocks, consolidated-drained triaxial compression tests were performed with mudstones, siltstones, tuff, weathered granite and so on. Maximum stress of applied confining pressure was about 30 MPa. Radial compression tests under confining pressure were also performed to study the mechanical properties under tensile stresses.From these series of experiments, it may be concluded that the relationships between confining pressure and strength (maximum and residual) are generally non-linear.These strength relations can be expressed as the following power function;(τ_m/τ_m0)=α(σ'_m/σ'_m0)^β where τ_m=(σ₁-σ₃)/2, σ'_m=(σ'₁+σ'₂+σ'₃)/3, τ_m0 and σ'_m0 are at the case of σ'₂=σ'₃=0. α and β are material constants for rocks and σ'_m>0. The value of α is generally about unit and in the range of 0.96-1.23 and β is in the range of 0.44-0.85.The normalization by τ_m0(=q_u/2) and σ'_m0 (=q_u/3) makes possible to represent with the same values of parameters α and β, the strength reduction due to scale effect and strength relation of sedimentary rocks which have the same geological history and of granites of various degrees of weathering which are distributed in the same petrographic province.The applicability of proposed power function to the hard rocks and rock masses were investigated. Consequently, it is clarified that the proposed equation can be applied to the hard rocks which has the unconfined compressive strength of 20-200 MPa and also applied to the closely jointed rocks which can be regarded as the model of rock masses.

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In order to determine the cyclic strength or resistance to liquefaction of tailings materials, six tailings sampled from different tailings dam sites in Chile and Japan plus one artificially ground quartz powder were tested in the laboratory using the cyclic triaxial shear test apparatus. Coarse grained materials and fine grained materials were sampled separately from laminated profiles of deposits at each tailings dam site and the tests were conducted each on these two kinds of materials. The cyclic triaxial test results showed that for the coarse grained tailings called sand, the cyclic strength was a little lower than that for the normally encountered clean sands having almost identical grain size characteristics. For the fine grained tailings called slime, the cyclic strength was shown to depend largely on the consistency characteristics. The fine grained tailings which are identified as being nonplastic showed much smaller cyclic strength than the tailings having a plasticity index on the order of 15 to 20.

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