Fatigue tests have been performed on soft to hard rocks to study the method for evaluation of a strength of rock against long-term loading. The dependence of the static strength on stress rate can be expressed as σ=a+blogσ. In cyclic loading fatigue tests which with maximum stress ratio normalized by the compressive strength corresponding to cyclic loading stress rate, the S-N curve is independent on the excitation frequency. Experimental results indicate that the fatigue strength such as S-N curve under the long-term cyclic loading can be evaluated through fatigue tests at a relatively short frequency of 0.5Hz by using the static compressive strength corresponing to the cyclic loading stress rate.

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Several experimental equations by which the coefficient of permeability can be estimated from the physical properties like diameter of soil particle and void ratio, have been proposed so far. It is, however, difficult to judge which equation is better. In the present paper it is shown that the measurement of specific surface area according to the Kozeny-Carman Equation is very valid to estimate the relationship between permeability of soil and the mean diameter of soil void, and to consider the effect of physical properties like size and shape of soil particles on permeability.

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On a method for safety control of retaining wall, this paper proposes a back analysis based on inverse formulation method with simple model to estimate unknow parameters (such as lateral pressures acting on retaining wall and elastic constant of soil) more quickly and more stably at construction site. And after investigation with some calculation examples about the validity of this method, it is verified that practical solution of wall displacements and axial forces can be gained. Finally, compared with measurement data, it is shown that the result of prediction analysis based on these assumed parameters is on the safer side.

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The soil permeability representative of a clay foundation, sometimes referred to as mass permeability, can be evaluated inversely using observation of settlement-time behaviour under embankment loading when the load intensity is normalized with the undrained bearing capacity of the clay foundation. Elastic plastic soil parameters should be determined so that the undrained bearing capacity may be predicted properly. The procedure mentioned above is shown applicable to practical design problems through examinig numerical simulations of the design of precompression for improving a soft clay foundation.

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Soils are regarded as a mixture which consists of various sizes of grain particles. The stress-strain behavior, therefore, depends on the properties of the particles and its grain size distribution.
The purpose of this study is to predict the strength properties of mixed soils based on the consideration of soil structure. The soil structure is regarded as consisting of skeleton of coarse particles and matrix constituted by fine particles and water. The stress distribution in the mixture is evaluated by using the strain energy of the mixture. The relationship between stress ratio and fine fraction at critical state is derived by using the proposed method. Its validity is confirmed from the triaxial compression test results for two types of the mixtures and other experimental results.

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Evaporation process from granular porous media and rocks under artificially regulated conditions is studied experimentally and theoretically. Evaporation volume from opening surface of cubic samples is measured in high accuracy, and the decay process of void water by evaporation with elapsed time is visualized by means of a microscope apparatus. It is disclosed experimentally that evaporation occurs through three different steps of water content in voids, and the evaporation process can be explained by numerical solution of coupled heat and mass equations.

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This study investigated stabilization effects for clay and sandy soils using two types of lime-flyash mixtures as stabilizing reagents. The results are summarized as follows.
1) Flyash containing small amounts of gypsum and lime could be used as a soil-stabilizing reagent without any further addition of lime. 2) Small amounts of alkali in the flyash were found to stimulate the occurrence of pozzolanic reactions. 3) Ettringite, which formed during the curing process, helped to strengthen treated soils. 4) The increase in strength for kaolinite was considerably greater than other clay mineral specimens. 5) Among the sandy specimens, weathered samples containing larger amounts of clay showed a greater increase in strength. 6) Stabilization effects could be estimated from the ignition loss of clay minerals. Furthermore, it was discovered that there was a relationship between strength and ignition loss values of 110°C-200°C.

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This paper presents some methods which determine the elastic properties of anisotropic rock masses by interpreting the results of borehole jack test and water chamber test on the basis of two-dimensional anisotropic elastic theory. In the first part, mathematical formulations of two approaches for borehole jack and water chamber (with circular lining) tests in the medium having circular or elliptic hole are given, then the charts for determination of orthotropic elastic properties of rock masses are prepared by several graphical representations.

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In this paper, we propose a new methodology for parameter identification of groundwater systems. Observations of either groundwater heads, pumping rates or hydraulic conductivities estimated from permeability tests, can be used to identify the distributed parameter systrem in a unconfined aquifer. Based on the extended Kalman filter algorithm, a finite element analysis is used to predict the groundwater heads and the pumping rates at the next time step, both of which are treated as the state variables in addition to the hydraulic conductivities. Finally, the proposed methodology is verified with the case using simulated data in a model of groundwater system, and is found to be reasonably accurate.

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The grading equation for decomposed granite soil is applicable to granular soils of various types other than decomposed granite soil. In this paper, for greater use of this grading equation, its features were theoretically clarified, and equations for determining important values such as mean particle diameter were derived. Transformation from the grain size distribution by ordinary weight basis to that by other criteria (number basis, specific surface basis) is theoretically described. Finally, several examples of the application of this grading equation are presented.

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For improvement of deep ground, heavy tamping method is a very popular technique. This technique has been carried out on a wide variety of soil types and conditions. However, its theoretical evaluation has not been fully developed yet, because its mechanism of improvement is too complex. A simplified method for evaluating the degree of improvement is proposed in this paper based on the results of some labolatory tests. Impulsive loading triaxial test apparatus was developed in this study for the purpose of testing soil elements applying the stress increments induced by dropping hammer. Furthermore, the compressibility of sandy soil under various stress increments in both drained and undrained conditions were investigated by using the apparatus. As a result, at first, it was found that in the case of undrained tests, the compaction of soil was produced by dissipation of induced pore water pressure after undrained loading. Secondly, it was concluded than in the case of drained tests, the change of void ratio was induced by both increments of effective mean principal stress and deviator stress.

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A new method of preparing cylindrial specimens for uniaxial compressive strength of sands stabilized were proposed. The method is easy to controll the density. Unconfined compression test and permiability test were performed on the specimens prepared by this method and the fundamental characteristics of the sands stabilized by chemical grout were studied. Then the effects of density on the strength were discussed and clear distinction between the effects of chemical grout and the density of sands were confirmed.

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Ground deformation and earth pressure in a fill ground induced by heavy tamping were investigated using simple marks and earth pressure cells buried during embanking and collected after tamping. The results showed that the ground deformation is concentrated in the cone trapezoidal area beneath the tamping hole and the earth pressure at the tamping point decreases rapidly with the depth. Centrifuge model test shows simulating this field test similar ground compression and pattren of ground deformation.

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To investigate the difference of undrained shear characteristics of undisturbed and remoulded cohesive soil, isotropically consolidated undrained triaxial compression tests were performed on Tokyo Bay Soil.
The observed effects of preparation methods of soil sample were discussed by a detailed look at effective stress path, strength and deformation characteristics. The test result that the undrained shear strength and deformation characteristics of undisturbed samples turned out to be larger than that of remoulded samples may be explained by the fact that the grain skeleton of the undisturbed samples offered greater resistance to compression than the destroyed grain skeleton of the remoulded samples.

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