The authors investigate into mechanism of behavior of pile foundation during ground displacement caused by liquefaction based on shaking table tests and numerical analyses. As a result, it is clear that characteristic of force depend on liquefaction-induced ground displacement is the drag force in proportion to the flow velocity of ground when the pore water pressure ratio was over 0.9 and the earth pressure caused by the ground displacement when pore water pressure ratio was below 0.9. They propose design method of foundation considering change of characteristic of ground displacement force.

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Exothermic and hardening properties of 72 hours retarded bentonite cement slurry material to maintain installation time of the material for stress distribution produced by retarding admixtures was investigated. Through these investigations, it was confirmed that temperature rising of the material could not be observed during the retarded term, strength development could be recognized by temperature rising and the maximum temperature of the material and the retarded term and strength development after retardation could not be influenced by temperature difference of the slurry after mixing and by mechanical action. The retarded material has been smoothly applied to the execution time restricted construction of deep earth retaining wall.

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Triaxial compressive stress was re-loaded to estimate the pre-stress using the Kaiser effect. In the case of cyclic incremental loading of differential stress until post-failure region, the remarkable AE increase appeared at pre-releasing stress level. The stress level at which the Kaiser effect was observed under the re-loading of hydrostatic stress corresponded to the pre-confining stress. The pre-confining stress, peak strength and residual stress were also able to be estimated under the re-loading of hydrostatic stress and differential stress from the Kaiser effect. Frequency estimated from ringdown counts and duration time of AE signal changed at the Kaiser effect point, which was determined by calculating the AE evevt count rate increment.

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For the disposal of high-level radio active waste, repository in deep underground has been considered. To design deep underground structure without any experience, it is necessary to employ a numerical method that can reproduce the governing phenomenon. In this study, MBC (micromechanics-based continuum model) that can reproduce sliding and opening of joints due to stress relaxation during an excavation is adopted, and a new design method is proposed. After comparing analytical results with measured convergence data and determining the critical value of maximum shear strain, the trial design is conducted. It is shown that a lining thickness is determined for different values of joint spacing and tunnel depth.

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It has already been proved from in-situ tests that the “Repeated grouting type ground anchor” using special grouting method is an anchoring method available to loose soil. In this study, a series of laboratory triaxial grouting tests with several types of ground, which were different coefficient of permeability, and laboratory model tests for sandy ground with loose density were performed in order to investigate the pull-out and grouting properties. The main conclusions maybe summarized as follows: 1) Anchor pressure bulb mode by this method was classified compaction grouting, fracturing grouting and their combined grouting; 2) Pull-out capacity due to “Repeated grouting anchor” increased several times as much as that of normal type anchor; 3) The mobilized mechanism of pull-out capacity and grouting characteristics were clarified based on the test results. In addition, a new construction management method was proposed for “Repeated grouting type ground anchor”.

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The prediction of back-fill settlement due to the excavation work is getting important, particularly in the urban area. The finite element simulation would be a suitable choice to provide the prediction. However, it is hardly feasible in practice to carry it out because input parameters needed in the F. E. simulation are not provided in advance. This paper proposes a simple prediction method of the back-fill settlement due to the excavation work. The proposed method is built based on monitored data gathered from a lot of actual sites. The method consists of two parts, that is, predictions of the maximum amount of back-fill settlement and the distance in which the back-fill settlement reach from the retaining wall.

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The authors performed laboratory tests for bending characteristics of frozen soil column with rectangular section whose tension side is reinforced by steel pipe. The tests showed an increasing tendency of the bending strength when reinforced. An analytical procedure is developed for the steel pipe reinforced frozen soil column as a composite material. The computed results show rather good comparisons with the relation of load vs. deflection as well bending stress at failure obtained by laboratory test if the frozen bond between the steel pipe and the soil does not break. The computed stress at the breakage of the bond under bending test is also coincident with the adhesive strength obtained by laboratory test. The authors applied the analysis to estimate a site scale condition and estimated how much soil volume to be frozen can be reduced if the steel pipe reinforced frozen column is used.

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Deformation prediction of the ground in tunnel excavation is important in order to examine the impoact on the neighboring structures. In this paper, an elasto-viscoplastic soil/water coupling finite element analysis is carried out for a mountain tunnel constructed in unconsolidated sand layers in Kanazawa. The applicability of this numerical method to the tunnel excavation analysis is examined by comparison between the analytical results and the measured ones. The effects of the analysis region and the mesh division on the results are also examined. It is shown that the analytical results match approximately the measured ones.

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Centrifuge model tests were conducted to clarify the mechanism of redisutribution of earth pressure around ECL tunnel. The tunnel was modeled by rubber balloon filled up by deaired water so that the steel fiber reinforced concrete used for ECL could be regarded as liquid before hardening. And some cases of ECL tunnels were analyzed with the redistribution. Following conclusions may be drawn by these studies. (1) the earth pressures around the ECL tunnel were influenced by fresh concrete pressure intensely. (2) redistributed earth pressures were defined by concrete density, depth and pressure at the crown. (3) analysis results were nealy equal to the in-situ measurement at Kohnan Common Duct Work in Okayama.

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This study examines the relationship between earthquake damage of Hachinohe city in Aomori prefecture due to the 1994 Far-Off Sanriku Earthquake and geological characteristics based on microtremor measurement and response analysis using multiple reflection theory.
It is concluded that 1) Water supply damage is more affected by boundary of the ground characteristics than predominant period and acceleration of seismic wave. 2) Ground motion spectrum depends on thickness and hardness of soil layers shallower than bearing stratum (N-value 50). 3) Damage on structures is influenced by predominant period and acceleration of seismic wave. So microtremor measurement is very effective for estimation of seismic damage.

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The purpose of this study is to estimate the sample scale effect on consolidation characteristics, permeability and secondary consolidation of an organic soil. Large sized specimens of organic soil, having a diameter of 300mm and a thickness of 100, were prepared for consolidation tests. Specially designed automated large size consolidation apparatus, capable of measuring the ring friction and the horizontal coefficient of consolidation, was used to investigate. Consolidation on large sized specimen is found to provide high quality data without the influence of disturbance and non-homogeneity. Compared to ordinary soils, organic soil was found to possess significantly longer coefficient of consolidation anisotropy between horizontal and vertical directions. It was also found that preloading of the organic soil specimen to 1.5 times the final consolidation pressure would reduce its coefficient of secondary consolidation in normally consolidated region by 10 times.

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Two types of model tests have been performed on ground anchorages using coned disk springs to determine the applicability of this prestress-maintaining technique. One type was a reduction model test of anchorage load and the other was a slope model test with anchorages. This paper also proposes a long term anchorage working load prediction method using a visco-elastic model.
The reduction in anchorage working load with coned disk springs is one half to one third of the reduction in anchorage working load without coned disk springs. Long term anchorage working loads are obtained by the prediction method with and without coned disk springs.

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The effect of subsurface liquefaction on the seismic behavior of partially saturated soil was discussed. The effective stress analysis with unsaturated seepage was presented and verified based on the results of unsaturated seepage experiment. The one dimensional analyses of the liquefied ground during the 1995 Hyogoken-Nanbu earthquake was performed. We discussed the effect of the unsaturated seepage characteristics, permeability and input motion on the generation of excess pore water pressure in partially saturated soil. The numerical results showed that the seepage to partially saturated soil caused the delayed dissipation of excess pore water pressure in the subsurface liquefied soil, and liquefaction of surface partially saturated soil with increase in the degree of saturation.

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This is one of the studies aimed at quantitative evaluation of the indices for rock mass classification that deals with “judgment method by the hammer tapping”. In this study, we examined the tapping test and unconfined compression strength using boring core of shale, which was gathered at Kitagou in Miyazaki for application of practical problems. As a result, we showed that “response sound pressure pulse inclination” can be applied as a quantitative index, like N-value of soil boring log, for strength and ductility of stratum in layered formation rock as shale, and aeolotropy by lamination side of shale was grasped by this index.

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It is important to take into account scale effects on fracture geometry if the modeling scale is much larger than the in-situ observation scale. The scale effect on fracture trace length, which is the most scale dependent parameter, is investigated using fracture maps obtained at various scales in tunnel and dam sites. We found that the distribution of fracture trace length follows negative power law distribution in regardless of locations and rock types. The hydraulic characteristics of fractured rock is also investigated by numerical analysis of discrete fracture network (DFN) model where power law distribution of fracture radius is adopted. We found that as the exponent of power law distribution become larger, the hydraulic conductivity of DFN model increases and the travel time in DFN model decreases.

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Near-field effects are known to mask the correct arrival time of shear wave. The characteristics of near-field effects involved in laboratory bender element test were thoroughly examined in tests on clays. On the basis of test results, it is manifested that the travel time of shear wave should be taken as “start-to-start” between two instants at generation and at reception of shear wave. It is suggested to perform bender element test with input pulse using various kinds of wave form over a wide range of frequency. It is also preferred to employ incremental loading steps to reach the prescribed consolidation stress. It is demonstrated that the G-value of natural clay in laboratory bender element test coincided well with comparable G_f from in-situ seismic survey.

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This study aims to estimate the sample quality of the stiff clays obtained in Amagasaki site, Osaka Bay site, and Kyoto site, and examines if the variation in its consolidation yield stress profile was caused by the variation in residual effective stress of the sample. The samples of these stiff clays have good quality from the practical viewpoint. Within the range of this sample quality, the over consolidation ratio is constant regardless of the degree of disturbance. We conducted three sets of constant strain rate consolidation tests at different setting conditions, with and without soaking in water. From these tests, we could confirm that the consolidation yield stress do not change due to the variation in degree of release of the effective stress.

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Recently, the solution type permanent grout for the countermeasure against liquefaction beneath the existing structures was developed and was adopted in several sites. In this paper, permeability of chemical grout material and strength property of improved soil by injecting the new chemical grout are studied. These tests show this new chemical grout material has high permeability and ability to increase strength against liquefaction. Because this chemical grout material is diluted by pore water during injection, expected strength is decreased by this dilution. In order to improve the strength of soil using this solution type chemical grout, consideration of dilution rate by pore water is appeared to be very important.

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This paper describes an approach for solving radionuclide migration in fractured media. In this approach, a three-dimensional heterogeneous channel network system is constructed using a stochastic discrete fracture network (DFN) simulator. The Laplace transform Galerkin finite element method was adopted to solve radionuclide migration in a complex network system for a long period of time effectively. Preliminary radionuclide migration analysis was performed for fifty realization of a block-scale DFN model. The total radionuclide release from all packages in the repository was estimated from the statistics of the results of fifty realizations under the hypothesis of ergodicity. From the result, it was found that large water-conducting features have significant impacts on the radionuclide release from the repository, and thus are important for the performance assessment of geosphere.

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This paper investigates the applicability of geostatistical models of hydraulic conductivity. The model studied herein are statistical properties of exponential model, autoregressive model, and power model in addition to 1/f model which authors have proposed. The results show that the variance is not uniquely determined in the former three models because the change of the variance depends on the domain size in both exponential model and autoregressive model and depends on the resolution in power model. On the other hand, in 1/f model, the variance is uniquely determined regardless of the domain size and the resolution. Moreover, the 1/f model can reproduce well the observed variogram.

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Pattern formation is often observed on the uniform (or macroscopically uniform) materials subjected to loading or deformation. In order to reveal the mechanism of pattern formation, we here investigate the mathematical structure of the bifurcation of a three-dimensional uniform domain with periodic boundaries by the group-theoretic bifurcation theory. First, we derive the concrete form of the bifurcation equations for three-dimensional uniform periodic materials by extending the results for two dimensional ones in a straightforward manner. Next, the symmetry of the kernel space of the bifurcation point and that of the bifurcation paths are classified by solving the bifurcation equations. Last, we conduct three-dimensional pattern simulation of the bifurcation phenomena of rocks and minerals in which the joint structure is observed.

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The authors had carried out some kinds of trapdoor experiments and had discussed the mechanical behavior of a tunnel excavation. Moreover, they had developed a three-dimensional trapdoor tester and had performed tests with it. Based on the knowledge and issues in their past research works, the authors improve their three-dimensional trapdoor tester, and both single and multiple trapdoor experiments are conducted in this paper. In multiple trapdoor experiments, which are proposed for use in the excavation of tunnels, it can be confirmed that the process of lowering trapdoors, that is, the excavating process, strongly affects the distributions of earth pressure and ground surface settlement. When lowering trapdoors, deformation occurs in the direction of the loosened area because a loosened zone has already appeared due to the lowering of the previous trapdoor. Therefore, an unbalanced distribution of earth pressures can be found.

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In order to make clear static and dynamic movement of a tunnel face and to assess the stability of the face, three dimensional model experiments of three kinds have been conducted. From the experimental results, it is made clear that excavation prosess of the tunnel face should be taken into account in the experiments to seize the essence of the failure phenomena. Active earth pressure and total force of it measured at the static experiments, which act on the earth retaining structure placed at the tunnel face, show almost the same value calculated by two-dimensional Rankin earth pressure theory. By developing this theory, safety factor equation is proposed for stability assessment of the tunnel face. The results of field measurement at the site support the appropriateness of the safety factor equation proposed.

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This paper presents the results of an experimental investigation on volcanic coarse-grained soils with fines, which are produced by particle crushing. A series of cyclic undrained triaxial tests and one-dimensional consolidation tests were carried out on reconstituted specimens, varying Fc, OCR and Ip of fines. The test results showed that liquefaction strength of specimens with OCR=1.0 decreases with the increase in Fc. On the other hand, liquefaction strength and consolidation yielding stress of overconsolidated specimen increase with the increase in OCR and Fc. Moreover, the amount of particle crushing is decreased with the increase in Fc. Therefore, it was considered that the strength increase due to fines induced by particle crushing depends mainly on the increment of particle to particle contacts.

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To examine the effect of the fabric anisotropy of sands on the initial shear modulus, the shear wave velocity in three different directions was measured by the bender element method on specimens with different fabric anisotropy. Furthermore, to examine the effects of the induced anisotropy, a series of bender element and cyclic torsional shear tests was performed under various anisotropic stress conditions. Test results showed that; 1) the initial shear modulus obtained from the shear wave for propagating and vibrating parallel to the bedding plane is higher than the other two kinds of moduli, 2) these two moduli are almost same irrespective of the fabric anisotropy, 3) the measured initial stiffness decrease gradually from the values estimated by an equation as the stress state approaches to the failure criterion line. This degradation can be expressed by a proposed new function.

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Cement treating technique like deep cement mixing method was generally used for stabilizing soft ground, however, dredged soil treated with low quantity of cement has begun to be utilized to construct a slope of seawall structure. For example, in Japan, a cement treated dredged soil was utilized to the intermediate buffer layer between the double layered impermeable sheets of a waste reclamation landfill. Since the waste reclamation site is usually constructed on a clay deposit with low permeability, very large settlement and deformation may occur during and after the waste reclamation, thus the cement treated soil layer is required to have high deformability. In this study, a series of laboratory tests was carried out to investigate the mechanical properties of the cement treated dredged soil.

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In Kagoshima Prefecture the pyroclastic flow deposits are widely distributed. Shirasu is a non-welded part of pyroclastic flow deposits and classified into sandy soil. Furthermore Shirasu is divided into the primary and secondary ones. The primary Shirasu forms the Shirasu plateau and the secondary Shirasu forms the alluvial plains along the coastal line. It has been found that the mechanical properties of Shirasu ground are qualitatively different from common sandy ground, but the data are not enough quantitatively to estimate the mechanical properties for design. In this paper several in-situ tests are carried out to estimate the mechanical properties of primary Shirasu ground, the obtained data are compared with those of common sandy ground and secondary Shirasu ground and the results are discussed.

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The (rammer) weight falling method for managing soil compactions has been studied in several research organizations. Two kinds of methods were proposed previously which measures acceleration values and in addition load values at the collision to judge the degree of soil compactions indirectly.
This paper proposes a direct method for determining the degree of soil compactions and estimating the static values of bearing capacities, instead of using accelerometer which is doubtful in dynamic response, from the measurement of load values at the collision solely.

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