On the basis of consideration on dynamic deformation test data of geomaterial, the author defined a physical parameter, namely, Momentary Deformation Modulus abbreviated as MDM that means the secant stiffness at very small strain near the origin in the every moment the latest maximum strain comes out under cyclic loading. Then, the author proposed a cyclic stress-strain model named MDM model that uses a skeleton function considering the maximum strain dependent change of the Momentary Deformation Modulus, applying the Masing law to the skeleton function. Besides, the author proposed a new hysteresis law and a determination procedure of parameters of the proposed model, and made the difference clear between the past hysteresis models and the proposed model. Furthermore, the author showed the flexible applicability of the proposed model by means of evidence that it could simulate the real stress-strain relationships of the quite soft soil and the extremely hard steel.

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This paper discusses the significance of self-weight of a pile, shear zone around a pile and stress distributions in a pile. The modification to compensate the difference in load transfer between head-down and pile-toe load tests is proposed. The self-weight effect was discussed based on the pile-toe load test results of 11 drilled shafts. The difference in shear zone was analyzed by use of load transfer curves of 20 drilled shafts. Furthermore, equivalent head-down load-movement curves of 2 drilled shafts on gravel layers were compared with the curve of a head-down load test and the analysis to compensate the effects gave reliable results.

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A number of researches have been performed to identify the conditions under which the liquefaction occurs. Moreover, the characteristics of liquefied soils under seismic excitations have been investigated by recent studies. A little have been studied on the post-liquefaction process although its characteristics would be important for understanding the mechanism of the liquefaction-induced ground movement and the related damege to the structures. In this papar, therefore, a simplified post-liquefaction theory is derived based on the sedimentation of sand particles, and after its validity is confirmed by the simulation of the recent experimental works.

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Freeze-thaw-shear tests are carried out in order to investigate fundamental properties of normally and overconsolidated clay after freezing and thawing history in the laboratory under triaxial condition. It is found that the frozen and thawed sample shows larger strength and smaller pore pressure development than those of unfrozen sample for the normally consolidated clay, and the change of shear strength and the dilatancy of overconsolidated clay depends on the overconsolidation ratio of sample.

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The shear band bifurcation mode and the progress of the discontinuous displacement field are numerically analyzed with a finite-element method. Kinematics and criteria of shear band bifurcation mode in multiplicative hyperelasto-plastic materials are presented, and a finite-element method for finite deformation with enhanced incompatible mode, which can kinematically express the discontinuous field, is adopted. Examination of the localization criteria reveals that the shear band mode can be detected even in the associative strain-hardening materials. Several numerical results show the significance and the effectiveness of the consideration to the shear band kinematics in the numerical analysis for strain localization problems.

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In order to determine the effect of grain size distribution on the unsaturated hydraulic properties of rockfill dam material, a series of large-scale laboratory tests have been conducted by using well graded samples with similar grain characteristics. The experimental results show that (1) the water retention characteristic curve of coarse granular material can be obtained precisely by using the Column method, (2) the unsaturated permeability coefficient can be obtained by establishing a steady state of the sample-mass, in maintaining a constant water flux on top of the soil column, and (3) the Van Genuchten model, which predicts very well the water retention curve of porous materials, do not apply to unsaturated permeability coefficient of such materials. Rather, the Irmay model predicts well the unsaturated permeability coefficient of such materials.

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One-dimensional numerical simulations of land subsidence due to dewatering were preformed based on the soil-water coupled finite deformation analysis. Naturally deposited soils are usually at overconsolidated state and those soils are mostly at structured state. In order to express loss of overconsolidation and decay of soil structure with loading, the super-subloading surfaces were introduced to the Cam-clay model. The following findings were obtained: (1) when dewatering exceeds a certain level, delayed consolidation with huge settlement is observed, which is concluded as the results of plastic softening of soils with plastic volume compression. (2) When multi-layered system is the case, delayed compression/consolidation of lower layers may occur even after the finish of the settlement of upper layers. This is due to the delay of propagation of the increase of effective stress that occurs due to dewatering.

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The results of the stress and deformation analysis of a center core-type rockfill dam by finite element method have been reported. Elasto visco-plastic effective stress analysis using the constitutive equation suggested by Sekiguchi and Ohta was used to simulate the elasto-plastic deformation behaviour of compacted dam materials under high overburden pressure. The calcuration results, settlement and the pore water pressure during construction, earth pressure distribution after the completion of construction were compared with measured ones, and the good agreement were verified. The applicability of this analytical method and the suggested input parameter determination procedure were confirmed.

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In this study, direct shearing tests of Sanjome andesite were carried out under three shear displacement rates (5×10^-5, 5×10^-4, 5×10^-3mm/s) and four normal stresses (10, 20, 30, 40MPa) by a servo-controlled testing machine. When shear displacement rate was increased by a factor of 10, increment of shear strength was about 1.2MPa. Relative increment against shear strength was about 6% that almost coincides with the values obtained in uniaxial tension and compression tests. It can be said that loading rate dependency of shear strength is similar to those of uniaxial tensile and compressive strength. The relationship between failure criteria and loading rate dependency was also discussed.

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Damped free vibration and resonance of soil are observed by using bender element system. Shear modulus and damping ratio are evaluated in two ways by applying the theory of resonance. Based on the test results on NSF-clay and Akita peat, it is shown that shear modulus can be estimated properly and is larger than that in case that the travel time is defined by the peak of receive wave on usual bender element test. In addition, it is also shown that damping ratio from these methods is almost coincident with that past report. It is proposed that bender element test can be performed in three ways; above two and an usual methods, so that information on damping ratio as well as shear modulus is given.

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Theoretical method of initial stress in viscoelastic rock is described by use of circular solid inclusion cell (SI-cell) due to stress release technique.
Using of the complex variable method and the correspondence principle between elasticity and viscoelasticity, three-dimensional stresses of rock are obtained by SI-cell with a finite radius of overcoring technique. Several examples are shown by graphyical representation and numeral results.

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We have developed and introduced new Shield Tunneling Method, ‘Combined Secondary Lining with 4-part 3-hinge Structure’ for construction of major branch sewer that is a main part of re-construction plan for sewrage system in Tokyo District. It is necessary to propose the design method to introduce the new structure because the segment is completely different from conventional system. We have conducted the load test using full-size model to verify the adequacy of our design. The test result concluded that our design method, using beam-spring model which is adopting 0 as rotating spring coefficient at hinge joint, same flexural rigidity as main body at rigid joint and the test result value as shearing spring coefficient at ring joint, is adequate.

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The design of the road embankment on the soft ground is based on the specifications and regulations so far. But it is scheduled to change to the performance design in the near future. In this paper, soil/water coupled FEM analysis is done to predict the long-term deformation of road embankment on the soft ground, and compared with measured ones, and comparatively good agreement is obtained. Some case studies of performance design by FEM are carried out. The countermeasures to the soft ground are studied and the optimum method from the viewpoint of minimum life cycle cost is found.

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The primary objective of this study is to investigate an anisotropic permeability through a single rough rock joint and its characteristic change due to shear displacement. Permeability approximation, which is represented by statistical first and second moments of aperture distribution, was used for this purpose. The shear-induced remarkable increment and anisotropy in the joint permeabilty were simulated, and their characteristics by a different spatial correlation function (; Gaussian and Exponential) of surface roughness were demonstrated. Obtained results were compared with those of Monte Carlo Simulation so as to present the validity of the current approach.

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An accurate evaluation of the grouting area in fractured rock is very important for designing the grouting pitch in the field. In this study, a method of determining the effective porosity and the grouting area of a three-dimensional (3-D) fractured rock mass are described. To evaluate the validity of this method, constant injection rate experiments were carried out in the laboratory. First, an experiment was performed on a gravel ground model. Then, a second experiment was performed on an axisymmetric cubic block model with gaps between the blocks mimicking fractures in rocks. The results obtained from the experiments agree well with proposed theory. The effect of gravity on high permeability fractured rock mass was also evaluated and the Hele-Shaw's seepage model was applied in explaining the laboratory results.

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The long face reinforcement method (FTT method) has been developed to stabilize the mountain tunnel face and to form the reinforced ground zone ahead of the face that restrains the expansion of the influence of the tunneling works to the surroundings. The effectiveness of this method was evaluated on the basis of the measured results obtained from a tunnel in poor geological condition. And also the three dimensional numerical analysis was carried out to verify the measured results.
The outcomes indicate that the long face reinforcement method has the significant effect to restrain the extrusion of the ground ahead of the face, and to reduce the pre-loosening zone of ground.

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The residual state means ultimate steady shear state after large deformation. The ring shear apparatus is considered to be the most suitable apparatus for forming this state in soils. However, a standard of ring shear tests has not been established, because shear deformation to reach the residual state is not clear; also, it is very difficult to measure pore water pressure in soils during shearing. First of all, the effectiveness of constant volume tests in ring shear tests was demonstrated in this study. Then, the residual state was not verified based on measuring pore water pressure but based on stress path obtained from constant volume tests. Finally, effective and simple methods to measure the residual strength were proposed.

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The seismic imaging method which surveys geological condition of ahead for tunnel face in the mountain tunnel are well known. However, it is not classified that this method can be applied to all of rock mass conditions, especially, in case of the rock masses including many fracture zones, it is important to research the degree of application of this technique because these rock masses are exciting many locations in Japan.
In this paper, this technique was applied on Hida tunnel construction site. As the result, it is clean that the geological conditions can be obtained by this method

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Simulation test for the process from sampling to unconfined and triaxial compression tests on undisturbed highly organic soil are performed with different anisotropic consolidation stress condition. The influence of anisotropy of consolidation stress on residual effective stress and unconfined compressive strengths are examined. From the test results, it is found that the unconfined compressive strengths decrease with the degree of consolidation stress anisotropy. It is also found that the unconfined compressive strengths of highly organic soil obtained from the tests of different anisotropic consolidation stress can be reasonably corrected by applying a simplified method which is formerly proposed by the authors.

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