A previously developed method for computing the progressive rise of pore pressures in saturated sands subjected to cyclic loading has been adjusted to fit data obtained from triaxial torsion tests. Also, the method has been incorporated into a computer code for the computation of pore pressures based on shear stresses obtained from an independent earthquake response analysis of the ground. The method has been applied in three case studies involving sand deposits where actual acceleration records were obtained during recent major earthquakes. The predicted behavior of the sand deposits has been compared with the observed damage related to the deposits.

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The residual soils (called Masado in Japan) derived from weathering of granitic rocks are tested to make their shear strength clear by the improved direct shear tests on their undisturbed samples coated by hard gypsum plaster. The shear strength of Masado is closely related to two weathering indices; i.e., porosity and ignition loss. The apparent cohesions and the internal friction angles determined by the direct shear testes on small size samples under constant volum eand constant normal stress are well in accordance with those determined by the drained triaxial compression tests on large size samples (Shono, et al., 1975). When concerned especially with clayey and silty Masados, the failure envelope derived from the direct shear tests under constant volume and constant normal stress is never straight. This is due to the reason that breaking of weathered particles occurs during the shear failure under relatively small normal stress less than 6 kg/cm².

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The paper concerns the problem of one-dimensional consolidation for clays exhibiting creep under constant effective stress. A stress-strain-time relation relevant to the consolidation process is deduced, by assuming K₀-conditions, from the stress-strain-time theory developed by Murayama et al. (1974) and Sekiguchi (1974). A numerical solution to the mathematical equations governing the consolidation process is presented, and based on the predicted settlement-time factor relations a method of determining the coefficient of consolidation is proposed. Discussion is made of the influence of both the duration of secondary compression during the preceding load and the maximum drainage distance on the consolidation behavior of such clays during the following increment of loading. In addition, it is shown that there is reasonable agreement between the measured settlement and pore pressure dissipation-time curves and the predicted ones for laboratory consolidation tests on specimens of a saturated clay for each of pressure increment ratios of 0.1, 0.5 and 1.0.

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Change in undrained shear strengths s_u due to swelling under K₀ and isotropic stress conditions were investigated for three saturated remolded clays. Test results indicate that the relationship between the ratio s_u/p, where p is the vertical effective stress at the end of swelling, and the overconsolidation ratio n is represented by a straight line in logarithmic plot. Moreover, the slope of this line is almost the same for both K₀ and isotropic stress conditions, and its value is closely approximate to that of (1-C_s/C_c), where C_c and C_s are compression and swelling indices, respectively.Based on the test results, the authors proposed a simple method of estimating the in situ undrained shear strength s_u for overconsolidated clays from a series of conventional laboratory test.Furthermore, the coefficient of earth pressure at rest K₀ and the pore pressure coefficient A at failure were discussed in relation to overconsolidation ratio n.

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In this paper a variational principle is introduced in which the Euler equations are the theoretical three-dimensional equations of consolidation in fully saturated and heteogeneous poro-elastic media with the fundamental consideration by Sandhu and Wilson. A finite element method is then used in both the space and time domains to develop a practical solution technique. Furthermore, in order to discuss the various problems and difficulties in applying this numerical method to the practical design of foundation settlements, the results of the analyses are compared with the observations on the Aiko test embankment for the construction on the Tomei Expressway. The calculated settlements and pore water pressure fields agree well with the measurements when the permeability coefficient can be predicted accurately, except the parts where plastic settlements occur. As previously pointed out, however, when the permeability coefficient obtained from the oedometer test is used, the field time-rates appear to be faster than indicated by the analyses.

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The safety factor which may be defined as the ratio of the resistance of a structure to the applied loads is intended to cover all the uncertainties about strength, loads and mechanical theories. In this paper, at first, mathematical structures of these uncertainties in the stability problem of an embankment are considered. Some points are discussed about the "constancy of coefficient of variation" of undrained strength in a natural ground and this constancy plays the role to express the transition process of a state of ground. Sliding failure is naturally defined as a probabilistic event because of the probabilistic representation of inhomogeneity of a ground and some errors and hypotheses in a stability analysis.The parameters of a probability distribution of failure are estimated under the evaluation of the utility of an embankment. For this purpose, the loss function is defined by two factors, the one is a probability of failure and the other is a preference function. This definition shows that the Bayesian decision criterion is most reasonable.In a conventional safety factor method, the maximum likelihood estimator of strength is devided by a safety factor and a safety margin is subtracted from this quotient to get a design strength of a ground. This design method is compared with the presented optimum design.Some numerical examples show that the conventional safety factor does not always give a good approximation to the presented optimum design over the full range of a probable strength of a ground.

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A new stress plane in the three-dimensional stress space has been proposed on an idea that soil is one of the materials governed by the frictional law, i.e., the shear-normal stress ratio. The new stress plane is named "Spatial Mobilized Plane (SMP)". It has been verified by data of various kinds of shear tests including true triaxial tests that stress-strain behaviors of soil under three principal stresses can be uniquely expressed on the SMP. Furthermore, a new yield condition of soil J₁·J₂/J₃=const. (J₁, J₂, J₃ : the first, second and third effective stress invariants) has been also proposed on condition that soil yields when the shear-normal stress ratio on the SMP reaches a certain value. This proposed yield condition is in an interesting correspondence with the Tresca, von Mises and Mohr-Coulomb criteria.

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An X-ray technique is used for the determination of local strains in triaxial specimen of saturated Kaolin during shear under stress-controlled conditions. The axial and radial strain distributions in 1.5 in. diameter by 3.0 in. high samples contained between friction ends and lubricated ends are presented. The principal axes of local strains are found to coincide with the vertical and horizontal axes of the specimen. The overall axial and volumetric strains computed from the local strain measurements are in excellent agreement with the overall average measurements conventionally measured using a dial gauge and a burette. During progressive failure in compression rigid zones were found to develop at the two ends of the specimen. No rigid zones were observed during progressive failure in extension tests.

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