Three-dimensional displacements during large rock mass excavation were measured using a three-components underground inclinometer. From these, a vertical deformation (rebound), a horizontal deformation, a convergence time and a trend of non-linear increase of vertical strain by a removed load were clarified. And a practical elasticity coefficient was estimated by a removed load of excavation and a vertical deformation. Furthermore, the relation between a removed load process of a borehole lateral load test carried out before excavation and an elasticity coefficient was investigated. Based on these studies, the method of developing analytical model using a data of borehole lateral load test carried out before excavation and the risk control criteria during excavation were proposed.

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In this study, the liquefaction resistance and deformation characteristic after cyclic shear loading were tested by element tests for the improved sand by the permeable grouting method. The liquefaction resistance of improved sand, which has peculiar ductility, was evaluated by use of the reduction of shear modulus and the cumulative dissipation energy obtained by a strain-controlled test instead of a traditional stress-controlled test. The deformation characteristic after cyclic shear loading was evaluated by the residual strain obtained by a re-consolidation test and an undrained triaxial compression test after cyclic shear loading. In addition, the effectiveness of permeable grouting method against to earthquake loading was confirmed by an on-line testing, It is found that the occurrence of liquefaction and redidual deformation of improved sand after cyclic shear loading are restrained by improvement of permeable grouting.

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In this paper, a dynamic finite element method is proposed for earthquake analysis of the reinforced stabilized soil ground. The method is to solve an initial-boundary value problem by combing finite element method with particle discretization and soil-water coupling finite element method. Three cases of shaking table tests were simulated to verify the accuracy of proposed method. It is shown that the proposed method can simulate the observed behavior.

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Present evaluation of vertical soil resistance of piles is based on result of static loading test. However, vertical soil resistance of piles during dynamic loading with large load velocity may well be different from that during static loading. In this study, examination about effect of load velocity on vertical soil resistance of piles by dynamic loading test with hammering is carried out, including simulation of the examination by lumped spring model using unloading point resistance, at which the velocity of a shaft is almost zero. Consequently, the unloading point resistance is almost equal to static soil resistance under almost condition of piles, and the difference between end-supported pile and friction pile in dumping characteristic and the result of analyses using unloading point resistance are presented.

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A series of three-dimensional soil−foundation−structure coupled analyses of transmission tower is performed to investigate the strength of the entire system. Nonlinear finite element analysis is conducted to capture the progressive failure of the foundations and the buckling behavior of the tower. In the series of analyses, various landforms, load directions and neighboring of the piles are considered to evaluate the performance of the foundation under actual condition. The coupled analysis of the entire system reveals that the displacement of the foundation is influential on the collapse of the tower. Moreover, it is pointed out that the critical component in the collapse of the entire system drastically changes depending on the mode of external loads.

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This paper describes a study on grouting strategy for crystalline rock. Fisrt, grouting practices used in Nordic coutries are summarized. Their main characteristics are the usage of thick slurry of micro-cement, dense pattern of grout holes and simultaneous injection of plural holes, which enable both of high-level water sealing and shortening of grouting work. To investigate the applicability of thick cement slurry, high-pressure clogging test simulating real grouting work has been conducted. The test results indicated the possibility to prevent the clogging phenomenon of thick cement slurry, i.e. water cement ratio of 1.6, by increasing the inejection pressure gradually.

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In this research, two model tests were carried out for the clarification of the advance of consolidation and the prediction of the ground behavior on Vacuum Consolidation Method (VCM). One is the triaxial consolidation test combined with vacuum pressure, and another is the stage-loading test for the simulation of the fill construction with VCM. As the result, we confirmed that it can predict drainage discharge and pore water pressure of field. Moreover, VCM was expressed by Finite Element analysis, and the validity of modeling was confirmed. From the result of the numerical simulation by FEM, it is shown that it can predict the ground behavior on the fill construction with VCM.

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The existence and behavior of discontinuities in a rock mass are well known to govern the mechanical and hydraulic behaviors of the rock mass. The numerical model by which not only mechanical but also hydraulic behaviors can be predicted is of prime importance. However, there is no experimental apparatus by which the flow-deformation coupled behaviors of a discontinuous material can be seized. In this study, a new experimental apparatus is developed so as to seize the coupled behaviors, and the tests with associated to the coupled behaviors are conducted with the use of artificial specimens. It is revealed that the permeability of the specimen is affected by the deformation of existed or emanated discontinuities in the specimens.

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Earthquake observations of soft ground have been performed since 1990 in Tomakomai City, Hokkaido. And earthquake observations of a road embankment have been performed since 1996. Data have been recorded for 9 earthquakes. The seismic motions that were recorded have ranged from minor motions to motions strong enough to produce amplification in which the seismic behavior of soft ground and the road embankment is non-linear. This study uses these records to examine the nonlinear seismic behavior of a road embankment. The results show that the seismic behavior of soft ground and the road embankment is nonlinear, that a cross-sectional area of the embankment behaves as an integrated system, and that the low-order natural frequency is roughly the same in the ground as in the embankment.

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Bearing capacity failure of road retaining walls, of which foundation soil condition is not taken into account in the design practice, often results in the severe damage to road embankment during an earthquake. This paper proposes a simple method to assess seismic stability of existing masonry retaining walls. The seismic coefficient invoked in the method is derived based on case histories of damaged and non-damaged walls. It is shown that bearing capacity estimated based on blow count of the in-situ portable dynamic cone is an effective index to sort out seismically unstable walls from existing walls.

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A series of tests to examine the volumetric compression behavior of sand caused by cyclic shear tests is conducted. To investigate, stress-control cyclic shear tests are performed. Thus the volumetric strain of saturated sand under drained cyclic shear is compared with that of re-consolidation following liquefaction after undrained cyclic shear. In the stress-control cyclic shear tests, cyclic shear strain behavior depends on the drainage condition during cyclic loading. However, even if the apparatus of stress-control test is used, an evaluation with cyclic shear strain histories indicates that two amounts of the volumetric compression obtained from those two types of tests are same. This result is not influenced by any confining pressure. In addition, when there is initial shear, the volumetric compression caused by cyclic shear results in lower ratio than that of isotropic stress condition.

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