Four down-hole array records obtained during the 1995 Hyogoken Nambu earthquake are used to investigate the nonlinear characteristics of amplifications of vertical ground motions in various soils. Significant vertical accelerations were observed at some sites in this earthquake where soil deposits strongly behaved nonlinearly. The soil parameters under strong ground motions are identified by combining downhill simplex optimum method with multiple reflection theory. The nonlinear soil properties are evaluated by comparing the identified dynamic soil parameters with those under PS logging. The nonlinear seismic responses of both horizontal and vertical ground motions are calculated based on the soil parameters identified.

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The electorical resistivity prospecting is a useful method to detect the distribution of water, which is contained voids and fissures in rock mass, namely discontinuities in rock.
Authors firstly establishs the algorithm of inversion analysis to identify resistivity values through an extended Kalman filter, which can be constructed in visual form. Secondly the foundamental study is illustrated for application to the analysis of electrical resistivity method so as to develop the program for 3D-FEM. It is concluded that the inversion technique by a 3D-FEM, which we have established through an extended Kalman filter, works effectively.

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In this study, consolidated sandy soil was used in permeability tests as part of triaxial compression tests to learn about the water cut-off characteristics during the deformation process of chemically-stabilized consolidated sand. The results of the tests were arranged according to the hydraulic radius of soil and the brittleness of the homogenized gel of the grout. Then, by paying close attention to the strain ε_(k(ini)) that occurs when the permeability coefficient during deformation begins to rapidly increase, a proposal was made for the prediction and evaluation of water cut-off capacity during the deformation process using critical strain ε_o as an index.

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Several series of 1g model footing tests were carried out at laboratory to provide information which can be used for design of the spreading earthwork on soft clay. It was indicated from the results of these tests that (i) combination with nonwoven geofabric, (ii) confinement at the edge of geogrid and (iii) placement of sand mat were effective for increasing the bearing capacity of soft clay reinforced with geogrids.

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This paper presents a procedure which estimates a less-sampled variable such as the internal friction angle or the cohesion with acceptable precision using a better-sampled variable such as N-value. Incorporating the regression relationship between a better-sampled variable and a less-sampled variable into the cokriging method, the cross-covariance function is easily determined, then the better estimation of the less-sampled variable is obtained.
In a numerical example, the bearing capacities of four foundations supported a transmission tower are calculated using the internal friction angle and cohesion estimated by this proposed procedure. The calculation results are compared with those of calculated according to the current specifications.

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Heat transfer of ground which is assumed as a composition of soil grain and water is affected by various thermal properties of the materials. It seems that in case of real permeable grounds heat transfer by convection also should be considered in addition to the heat transfer by conduction. This paper describes FEM analyses in which the effects of conduction as well as convection are taken into account in heat transfer phenomenon. Then numerical results of parametric analysis concering the variation of different material properties likes porosity, specific heat, and thermal conductivity are discussed. Finally, presented analytical method is applied to the ground with linear heat source and a crack filled with water.

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In the ground improved by DEEP MIXING (DM) method up to the bearing stratum, it is expected that the displacement of the improved ground is comparatively smaller so that external forces acting on the DM body are mobilized in the process of horinzontal displacement of the DM body. External forces on the DM body were measured during the construction of reclaimed land. After various investigations on the stability of the DM ground as well as external forces, the following conclusions were derived. (1) The earth pressure in the active side developed to the active earth pressure as a result of small movement of DM body while that in the passive side remained as the earth pressure at rest. (2) The subgrade reaction forces on the base of the DM body found to be equivalent to the analyzed pressure considering the skin friction acting on the DM wall in the active side. (3) From these evidents, it was confirmed that the mobilizing process of external forces should be taken into account. (4) Further, some problems in the current design method were pointed out from this study.

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The monotonic and cyclic triaxial tests were performed on reclaimed sands sampled from Kobe Rokko Island. The effect of both confining pressure and relative density on the shear property of the soil has been considered. The research presented here was performed in order to understand the effect of soil compressibility and crushability on the monotonic and cyclic undrained shear behavior of soil. In addition, the cyclic triaxial tests on anisotropically consolidated samples were carried out for various combinations of initial static and cyclic shear stresses which are those expected on soil elements subjected to cyclic loading in the vicinity of quay walls which were damaged by earthquake. The cyclic shear strength tended to decrease with increasing initial shear stress. It was the opposite tendency from that for Toyoura sand. The quay wall based on the decomposed granite soil as a replaced sand was analyzed by a seismic circular arc method. The cyclic strength obtained by the tests were introduced into the analysis. The analytical result reasonably agrees with the actual damage case history.

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Seepage flow caused by heavy rain and flood is directly related to the slope stability of river embankment. Water content of soils in embankment fluctuates from day to day by the action of infiltration, evapotranspiration and the change in the water level of river and ground water. Seepage flow in the embankment is influenced very much by the water content of soils at the beginning, namely initial conditions. It is necessary to make clear the long range variations of water content of soils for analyzing the seepage flow and evaluating the stability of the embankments. The long term field observations of water content of soils with RI moisture meter have been carried out.
Through the results of observations together with seepage analyses periodic variations in water content of soils and specific features of moisture movement in the embankment are investigated.

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In order to determine ideal grouting conditions, one must estimate how different variables such as grouting condition and ground depth affect the shape and volume of chemical grouts. The results presented in this study were drawn from 300 laboratory tests, which included repetitions to ensure accuracy. Both the height and diameter of the test specimens were held constant at 30cm. When both the overburden pressure and injection rate is high, it is possible to obtain a spherical shape similar to permeation grouts. However the overburden pressure is high (irrespective of gel time), the volume of the solidified shapes is decreased about 15%-25%.

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The “diameter of estimating grain-size distribution” is defined/proposed, based on grain number-based distribution. This proposed “diameter” is found out a very valid index for method of classification of soils, from considerations/analysis of the relationships of the “diameter” of each classified soils and values of CBR, angle of shear resistance, coefficient of permeability and so on. The “diameter” of the grain size distribution of accumulated strata, of appropriate soils for construction works, and of easily liquefied soils, are calculated and presented for its utility.

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The authors discussed the effectiveness of the Slice Spring method (SS method) on typical soil failure problems by analyzing earth pressure, bearing capacity and stability of landslide acted the anchor force. The SS method is one of slice methods and provides dynamic statically determinate results. By the application of earth pressure and bearing capacity problems, a good results by the SS method are obtained conforming to known values. The SS method is also capable of analyzing the effect of anchor force rationally on the interslice plains in the landslide slope. It is verified that the SS method is capable of analyzing uniformly three typical problems concerning soil failure.

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The static soil-footing interaction changes with the applied load in bearing capacity problem. The interaction at the limit state is required as the boundary condition in bearing capacity analysis so that the rigidity of footing is, hitherto, idealized as perfectly flexible or rigid to simplify the problem. This study presents the ultimate bearing capacity of footing by taking account of the finite rigidity of footing and the change in soil-footing interaction. The lower bound theorem in shakedown analysis is employed to consider the interaction redistribution. The ultimate bearing capacities of footing against uniform and eccentric concentrated load applications are estimated and discussed in comparison with the reported experiments. The change in ultimate bearing capacity with the rigidity of footing is taken into consideration in view point of static soil-footing interaction.

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The vibration characteristics of penetration piles into the ground has not been discussed systematically in detail so far. As for the vibration performance of penetration piles into the ground, it has been elucidated that the vibrating motion of reaction force of pile tip can be classified into five categories. In this paper, in order to estimate the peak value of the classified vibrating motion, monitoring of vibration performance-reaction force of pile tip and acceleration of pile top-was carried out in sandy grounds, by means of the reaction force meter and acceleration meter attached at around the tip and the top of casing pile for the installation of sand compaction pile. Based on the monitoring data, it was elucidated that reaction force, acceleration and penetration time were systematically represented by dynamic force and mass weight of vibrator and piles. Furthermore, engineering application of the vibration characteristics of the penetration piles was presented.

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This paper describes time dependency of the constant volume shear strength of clayey soils.
Considerable difference between the experimental constant volume shear strength and theoretical value derived from the Sekiguchi-Ohta model is found out. It is thought that the difference is caused by time dependency of shear strength, which is experimentally quantified in this paper. Then, the constant volume shear strength is corrected by applying a correction factor, and reasonable agreement is achieved between theoretical shear strength and corrected experimental data.

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The cement powder grouting method (CPGM), which surface-treated microfine cement powder is injected with dry compressed air into interstices, has been developed for the purpose of enhancing the watertightness of soft rock grounds. This paper presents the physical properties of the surface-treated cement for the CPGM. Secondly, we report that the laboratory injection tests using the undisturbed samples taken from soft rock sites and sand specimens, the microscope observation of grouted rock samples, and watertightness and hardening characteristics of surface-treated cement. Finaly, we propose optimum ground conditions and standard specifications for the CPG

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To investigate the mechanism of long-term settlement of rock-fill dam, the field observations of impervious zone of a center-core type rock-fill dam were carried out. As a result of observation, the long-term settlement, occurred by some factors, is found distributed ununiformly in the core zone related to the scattering properties of fill materials, and is also increased when the water level draws down significantly. By these results, five factors which cause the long-term settlement were clarified.

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According to the both development of mechanics and electronics, the earthquake simulators for geotechnical model are used in centrifuge to take the place of that in the gravity field. But the similarity rule of a seismic behavior has been rarely investigated. This paper describes a series of shaking table tests carried out to compare the different scale model which is an embankment on a loose saturated sand. The sizes of reduced scale were the 1/3, 1/5, 1/10 in the gravity field and the 1/20 in the centrifuge. A good agreement was obtained in the dynamic behavior of excess pore pressures, acceleration response and surface settlement following the similarity rule respectively.

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In order to investigate the mechanical properties of stabilized Kaolin clay by cement type solidifier, consolidation tests, unconfined compression tests and triaxial compression tests were tarried out under various conditions. Various factors that influence the stabilized Kaolin clay and fundamental mechanical properties are obtained.
It is clear that the behavior of stabilized clay is similar to those of overconsolidated clays due to unloading, and quasioverconsolidated clay from consolidating for a long period.

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The technique how to evaluate the channel network system on the basis of many hydro-geological data such as geometry of fracture system, hydraulic head distribution, BHTV logging, results obtained by cross-hole tests and so on, is applied to a dam site that is mainly composed of granite and gneiss was selected. The structure of channel network system was successfully constructed on the basis of these geological information and the results of some cross-hole test.

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Some earthquake traces were discovered at around the embankment of outside moat of the Edo castle in a series of the remain investigation for the Yotsuya-Gomongai of the Edo castle at Yotsuya, Shinjuku, Tokyo. Sand dikes, fissures and a landslide were recognized as earthquake traces. According to site investigation, sounding and soil analysis for grain size, heavy metal and diatom, it was confirmed that source of supply of sand dykes was Tokyo Formation sand layer which is Pleistocene. The earthquakes induced the traces was specified from stand points of archaeology, seismology and geotechnical earthquake engineering. It was shown that Pleistocene, so called diluvial deposit, which had been thought hard to liquefy, could liquefy under severely strong motions.

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Laboratory tests presented tremendous effects to reduce surface tension on mechanical behaviors of unsaturated soil masses. Surfactants are noted for capable to reduce the surface tension, thereby diminishing the gas-liquid interfacial forces and the nonionic class not to receive the influence of soil particle electric charges. The potential of soil water test and unconfined compression test of unsaturated soil that is compacted by using nonionic surfactant solutions were carried out. The results of experiments showed that the optimum moisture content, soil suction and unconfined compressive strength decrease in proportion to decreases in surface tension and the compaction density increases conversely. As a application the obtained results are useful to development of rapid compaction methods.

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To investigate the mechanism of long-term settlement of rock-fill dam, an analytical study on the behaviour of impervious zone of a center-core type rock fill dam have been done. Factors affecting the long-term settlement were divided into five, consolidation settlement before reservoiring, secondary consolidation, settlement by reservoiring load, collapse settlement by reservoiring, settlement accompanying the draw down of water level. Next, quantitative study using finite element method, settlement prediction by past laboratory test results, and multiple-regression method was examined. Estimated and measured settlement showed comparatively good agreement, and the validity of supposed mechanism of long-term settlement was confirmed.

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In this paper, a fundamental general idea of rough set is described, which has attracted attention as a basic method to treat the knowledge that can not be distinguished in observation data, and the possibility of applying the rough set is discussed in acquisition of experienced knowledge from observation data.
A minimum decision algorithm is developed to derive useful production rules from a set of observation data. The applicability and efficiency of the algorithm is demonstrated by using an example of slope-failure diagnosis. Using the real data, it is confirmed that the method developed is useful for the acquisition of expertise, which is very important and inevitable to build a practical expert system.

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A dynamic centrifuge model test has been conducted to reproduce the liquefaction damage to a caisson type quay wall and its neighboring pile foundation observed in Hyogoken Nanbu Earthquake. The model, which was composed of including a gravity type wall, a 2x3 piles supporting structure and a saturated sand deposit, was constructed in a large laminar container. It has been found that 1) lateral ground deformation and settlements measured in the model are qualitatively consistent with the actual damage behavior observed in the field during the Hyogoken Nanbu Earthquake; 2) lateral deformation of the caisson is attributed to large shear deformation of the soil deposits beneath it; and 3) piles near the quay wall are likely to be damaged not only at their heads, but also at their middle parts when large lateral deformation of the caisson occurs.

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