The influence of the disturbance, stress history, rotation of principal stress and intermediate principal stress on the strength parameters in terms of effective stress of clay were investigated experimentally. The apparent cohesion c′ and ce of clayey soils in Japan were nearly zero. It was clear that apparent cohesion c′ and ce of soil which a montmorillonite content was less than 5% were nearly zero. The effective angle of friction φ′ didn't change by the disturbance, stress history, rotation of principal stress and intermediate principal stress. The φ′ of soil at the slip surface of a landslide was relatively small, about 20-35°. This is one of the reason that the landslide occur at the gentle slope.

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The practice, data-analysis methods and the data-interpretation techniques of the “vacuum-permeability test”, which is a method of detecting the loosened zone in rock mass by evacuating air from a sealed section of a borehole drilled in the rock mass and obtaining the air permeability distribution characteristics, have been described and examined in detail. A practical and reliable approach is proposed, and is shown that it is a promising evaluation method of loosened zone by conducting fields tests at various sites and comparing the results of existing methods and already known data.

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In case of a rock tunnelling by using the TBM, the modulus of elasticity of rock can be estimated at every advance with instrumentation of load and stroke of gripper jacks mounted on the TBM. This paper presents results of analytical and experimental studies on applicability of a rock deformability test using gripper jacks, comparing the standard plate loading test with a plate loading test under the same condition as a gripper is pressed on rock surface. On the basis of these analyses and experiments, it is revealed the possibility of a rock deformability test using gripper jacks of TBM to substitute the standard plate loading test.

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Time series of Momentary Deformation Modulus of soil are determined from nonlinear constitutive relations between deviatoric stress and axial strain. If one-dimensional data of the time series is discriminated as chaos by the Lyapunov spectrum etc., embedding the time series into a reconstructed multidimensional state space in accordance with the Takens' theorem leads to a set of many locating vectors; the dynamics of the locating vectors is defined in terms of fuzzy inference rules and evolution of the chaotic time series can be predicted by a prediction method of chaotic time series. Hysteresis curves corresponding to axial strain levels are derived from the predicted time series of the Momentary Deformation Modulus, Furthermore, the equivalent Young's modulus and the hysteresis damping coefficient are found through the derived hysteresis curves and compared with a result obtained by the dynamic deformation test.

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This paper is the final paper of three series papers, in which mechanical behaviours of unsaturated soil are analyzed in connection with the hysteresis in the soil-water characteristic curve. In the preceding papers, a model of pore water composition was proposed and examined by the isotropic compression tests. In this paper, the axial compression process of triaxial tests is analyzed. The constitutive equations are also developed through extending Cam Clay Model to dilatant and unsaturated soil. These equations simulate the test results well, however, frictional angle both at failure and at critical state must be inputted as the data.

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In order to apply one-dimensional elasto-viscous theory to practical problems, it is necessary to extend it to three-dimensional theory. With this in mind, three-dimensional creep tests under drained conditions were carried out on a reconstituted alluvial clay in a triaxial cell. A question of whether volumetric and shear viscous coefficients are independent of stress conditions or not, was examined. The result revealed that volumetric and shear viscous coefficients of clay are independent of stress condition. Furthermore, a unique plane termed ‘viscous coefficient plane’ exists in a space of e, logσ' and logη.

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This paper presents a finite difference method for solving problems of self-weight, large strain consolidation. Douglas-Jones' predictor-corrector approach for nonlinear parabolic differential equations, which is an implicit finite difference technique, has been incorporated with Mikasa's and/or Gibson et al.'s governing equations. Tridiagonal matrix equations and its solution procedure are derived for both double and single drainage conditions. Applications of the computer program developed have shown that the proposed method may be a promising tool for predicting large strain consolidation behavior.

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This paper describes a method for evaluating deformation characteristics of the ground using Cone penetration test (CPT) and Dilatometer (DMT). Correlation between shear modulus measured by Seismic cone, G_sc and values from CPT and DMT was studied for 8 different sites in Japan. It was found that for clayey ground, G_sc value can be well related with that from CPT and DMT. For sandy ground, however, these relations vary with relative density.

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It is difficult to simulate a large deformation phenomena with plastic flow after failure by using a general numerical approach, such as the FEM (finite element method), based on the infinitesimal strain theory. In order to investigate the behavior of tunnels excavated in soft rock mass, a new simulation technique which can represent large strain accurately is desired, and the code FLAC (Fast Lagragian Analysis of Continua) adopted in this study is being thought a best mean for this propose. In this paper, the basic principles and the application of the large strain analysis method to stability analysis and prediction of the deformational behavior of tunnels in soft rock are presented. First, the features of the large strain theory and some different points from the infinitesimal strain theory are made up. Next, as the examples, the reproduction of uniaxial compression test for soft rock material and the stability analysis of tunnel in soft rock are tried so as to determine the capability of presenting the large deformational behavior.

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In the DEEP MIXING (DM) ground there has been no practical construction control procedure (construction control system). In order to compensate for uncertainties not only in design but also in construction, it is necessary to build up a pratical and plain construction control system. Authors proposed a practical construction control system aiming at displacement, and applied it to the wall type DM ground improved up to a bearing stratum. Construction control system is necessary to be built considering the DM stabilizing mechanism, so the requirements of the way of installation of instruments as well as its system were defined. And stabilizing control indicies and construction control diagram were proposed. With its application to actual reclamation work, principal viewpoints of those were shown. The substances of all failure modes of the DM ground were investigated from the monitoring and analyses of this case, stability control criteria were proposed. And it was proposed that the modification of bearing capacity estimation of current design method was necessary.

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It is important to evaluate the deformability of discontinuity accurately to understand the behavior of rock masses. However, the evaluation of the discontinuity is hardly performed in the plate bearing test to understand the deformability of the rock masses, but the rock mass is considered as an equal homogeneous.
Then, in this paper the modulus of permanent deformation is applied as an evaluation method of the deformability of the jointed rock masses. As a result, the effectiveness of the modulus of permanent deformation in the evaluation of the deformability is shown by this classification.

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This study provides a new laboratory experiment technique for investigating the behavior of mud slurry supporting clay ground. On this technique, model ground is supported by pressured mud slurry under a centrifugal acceleration, and then the pressure of the slurry is reduced with monitoring the model ground deformation. Pre-consolidated clay model grounds were tested by this technique. Following conclusions may be drawn. (1) the clay model ground fails progressively with reducing the slurry pressure. (2) the ratios of the lower limit slurry pressure for supporting the ground and total vertical pressure of the ground show significant correlation with the undrained shear strength of the ground.

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A practical method for determining the residual strength from the experimental data in the ring shear test with clay has been proposed. A hyperbolic curve is applied to approximate the post-peak relation between the shear stress and the shear displacement, and the reisdual strength is determined as an asymptotic value of the hyperbola. The applicability of the method is supported by the test results of kaolin and natural clays under various test conditions. From considering the relation between the residual strength and the shear displacement based on the proposed method, the shear displacement at the end of shear process to determine the residual strength is dependent on nature of clays, normal stress and shear displacement rate.

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This paper describes the measurement results of site investigation and laboratory tests performed on soils sampled from the excavation slope.
The main concluding remarks derived from these studies are as follows; i) The inward soil of the excavation slope is neutral, on the other hand, the subsurface soil is strongly acidic. ii) The hydrogen-ion concentration exponent (pH) value of air drying soils decreases with an increasing elapsed time. iii) Unconfined compressive strength and deformation modulus increase corresponding to an increase of pH. Therefore, pH is the most important factor in considering strength-deformation characteristics of acid soils.

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To analyze the deformation of ballast regarding a part of ballasted track which is composed of crushed stone as an assemblage of coarse granular materials, cyclic loading and monotonic loading triaxial compression tests with stress condition of ballast under train passage were performed on samples of railroad ballast. As a result, the quasi-static characteristics of railroad ballast needed for numerical modeling were determined. It was revealed that the triaxial test results of railroad ballast basically provide useful data for elucidating plastic deformation of ballast in detail.

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In the application of the inverse analysis to the field of geotechnical engineering, it is important to take into account of the uncertainty of both the modelings and their parameters, because the information of the subsurface is limited in many cases. We propose a new technique for both the model selection and the parameter identification based on the ABIC (Akaike Bayesian Information Criterion) minimization method and the extended Kalman filter algorithm. A recursive calculation technique for ABIC with the Kalman filter algorithm is also proposed. We demonstrate the availability of the proposed technique. Particularly, 1) the prior stochastic distribution of the hydraulic conductivities, 2) the zonation, 3) the initial condition, 4) the boundary condition, 5) the specific storage coefficient and 6) the observation noise are selected as the optimum modeling. The order of the data using of plural pumping tests is also discussed. The estimation of the system noise playes an important role, because the system noise is influenced by the modeling error.

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As the method to estimate the bearing capacity of the pile during driving, dynamic pile monitoring methods are used. Shaft and point resistance of the pile are estimated by analyzing the wave forms of force and velocity measured near the pile head. However, if the driving force applied on the pile head was not enough to mobilize the full of the soil resistance against the pile penetration, measured soil resistance does not reach its ultimate value. In this case, it can be said that the estimate pile capacity from the dynamic testing was not equal to the results of the static load testing. In this paper, the limitation of the dynamic load test method were examinted from the theoretical and practical view points.

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This paper proposes an estimate method of ultimate embankment height for the soft clayey ground. The ultimate embankment height for imaginary model grounds are obtained from the soil/water finite element computation in which the imaginary viscosity technique is implemented. Based on the obtained ultimate embankment heights for imaginary model grounds, an estimate method of the ultimate embankment height for actual multi-layered soft grounds is constructed. Finally, the proposed method is examined by applying to actual failure records of embankments on soft grounds.

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It is well known that the acceleration response of the soft ground subjected to strong earthquake motion will be small due to softening of the ground. However this is inconsistent with the facts that the larger the earthquake damage is on the softer ground. In order to study the relationship between the seismic response of the ground and the earthquake damage, we performed centrifuge model vibration tests by using one dimensional shear column. The surface ground response is the input motion to super structures as well as the output response of the surface ground. From first point of view, it is found that soft ground plays an isolation role on short period super structure. From the second point of view, we have studied the frequency dependency of the shear stiffness of soft clay layer.

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A high embanked land was constructed by heavily compacting with soft rock materials for new Nanki Shirahama Airport. Though high compaction degree was achieved at each layer of an embankment, significant settlements were observed in the embankment after heavy rainfall during construction. It was found that the settlements were induced by intensive water seepage due to heavy rainfall and they were obserbed at specific locations in the embankment compacted under the condition of no rainfall or light rainfall. The authors carried out a series of laboratory settlement tests in seepage condition on highly compacted test specimens of soft rock material and derived a conclusion from the test results that increasing the compaction degree of the embankment more than 95% was very effective for decreasing the settlements. The settlements due to the water seepage could be decreased sufficiently at the actual embankment.

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A numerical analysis was conducted to estimate the movement of a shield tunneling machine accurately. This analysis simulated the movement of the machine, that is, the process of the angle change and the forward movement. The validity of the method was checked by comparing the coefficient in mathematical models estimated by the analysis with the data of model experiments and practicall tunneling projects. Furthermore, the estimated values of some parameters in the analytical model were compared with those from the simple method which was proposed by the authors previously. It was clarified that this method estimated the shield movement more accurately than the simple method.

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