The Great Kobe Earthquake (M_j = 7.3) struck the southern part of Hyogo Prefecture on January 17, 1995. Distribution of damaged houses due to this earthquake was like a belt. In order to understand this mechanism, the detailed geotechnical information database system was constructed by Kobe Local Government, in corporate with many kind of geotechnical engineers and researchers. This database was named as “Kobe JIBANKUN”. In this paper, we described the outline of this database and study cases that uses it. In addition, the problems and difficulties on maintenance were mentioned and some future problems were pointed out.

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It has often been indicated that the prediction accuracy of horizontal displacement by finite element analysis is inferior to vertical displacement (settlement). In this study, a new constitutive equation of the natural clay deposit was proposed for the purpose of improving the prediction accuracy of ground deformation. Then, the applicability of the proposed model for K₀-consolidation tests in a triaxial cell was examined and the finite element analysis using the field measurement data of the large scale embankment were carried out. As the result, it was proven that the proposed model appropriately reproduced the element behavior of natural clay deposit in comparison with Sekiguchi and Ohta's model. And, the proposed model can predict settlements and horizontal deformations of large scale embankments at the good accuracy.

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Since there are many embankments of irrigation tank in Japan, the method like asset management is needed to carry out the effective maintenance. In this paper, the method to examine the life cycle cost with regard to the heavy downfall is presented by using the statistical approach using the data at the disaster at Awaji island in 2004. The failure probability due to heavy rain is obtained by using the data base of irrigation tank, GIS of fine DEM and multi-spectral data. Then the cost for disaster is estimated by using the information of data base. The risk as a function of time is obtained by analyzing the rain fall data. Finally it is shown that the management is carried out to minimize the life cycle cost for the repair method and timing of repair.

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To evaluate the sample quality, shear modulus (G) and suction (p'_r) were measured for specimens extruded from sampling tube under unconfined condition. From a series of tests, it is found that G and p'_r values decrease with disturbance and these values exhibit a strong correlation. Furthermore, G was measured under various effective confining pressures (p'_m) by consolidation and swelling or by applying cyclic loading under undrained condition in the triaxial cell. As a result, it is revealed that G value is calculated by p'_m value regardless of different ways for changing the p'_m values and G value increases with as square root of p'_m. In-situ G values estimated by using laboratory test results are about 70∼80% of G_f values estimated from cone penetration test results.

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Imaging technique by passive measurements of vibration has been developed in order to use for investigation and development in a high level nuclear waste disposal repository. The drilling-noise of core-boring was recorded in a mining gallery, and characterization of the signal was conducted with a room experiment. Because the obtained signal was low quality with cyclic noises, the signal processing techniques such as adaptive filtering and 3D hodogram analysis were applied. Finally, the imaging results were reasonably consistent with the geology estimated from rock core samples. This paper presents the possibility of utilization of various passive vibrations to image subsurface structure at very low cost.

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For performance-based design of pile foundation, it is necessary to develop the practical prediction method to forecast long-term displacements of pile foundation. Many prediction methods have been proposed, however, it is still need to be developed due to the difficulty in evaluating the interaction of pile-soil-pile system, or in considering the long-term displacements accompanied with consolidation settlement. In this paper, the applicability of soil-water coupling elasto-plastic FEM with appropriate pile model to the prediction of deformation of pile is verificated in comparison with actual load test for single pile. Further more, the prediction for long-term displacements of actual pile foundation with soil-water coupling elasto-plastic FEM is conducted, and the long-term behavior of pile foundation, the mechanism of uneven settlement, the load sharing system in pile foundation are examined carefully.

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The aim of this paper is to study spalling in soft rock excavation. During the test cavern excavation of the radioactive waste disposal project, spalling occurred. Therefore, it has been estimated performing the stress path simulation test and measuring the induced stress. In the stress path simulation test, the splitting failure has been confirmed under low confining stress. In the induced stress measurements, the rock mass around the cavern has shifted to the low radial confinement. Hence, spalling in soft rock was interpreted by the splitting failure caused by the induced stress under low confinement. Furthermore, the failure zone was proved by the numerical analysis applying the criterion based on the results of the above triaxial test.

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According to the present radioactive waste geological disposal concept, a disposal facility is constituted from the bentonite engineered barrier, cementitious engineered barrier and natural barriers. In order to obtain the validity of the geological disposal concept, the high impermeability of bentonite-engineered barrier is necessary. Therefore, many various laboratory tests were implemented. There are, however, few researches which summarized these test results integratively in the viewpoint of soil mechanics. In this paper, both interpretations of extraordinary swelling and compression behaviors of the compacted bentonite were discussed based on the soil mechanics using constant water-content line and constant degree-of-saturation line in the e-lnσ_ν' plane.

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The lining concrete was a main support member in an ordinary tunneling method, but, in NATM, it is not to support external pressure except a special ground condition showing squeezing. Therefore, as long as the condition is satisfactory, lining concrete is omitted, and a big economic effect occurs. For abbreviation of lining concrete, shotcrete was evaluated as a temporary structure conventionally, but convenient and certain technique to evaluate it as a permanent structure is necessary.
In this study, we suggest the technique and a method that shotcrete is evaluated as a permanent structure using field measurement of daily management.
And we apply the method to Shinkansen section and show specific coverage.

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A conceptual model is presented to follow the evolution of permeability in siliceous rocks mediated by pressure solution. Specifically, the main minerals of siliceous rocks that are quartz, cristobalite, and amorphous silica, are focused to examine differences of the permeability evolutions among them at effective pressures of 1, 5, and 10 MPa, and temperatures of 20 and 90 °C. The rates and magnitudes of permeability reduction increase with increases of the pressures and temperatures applied. Ultimate permeabilities reduced by the order of 90 % at the completion of dissolution-mediated compaction at 10 MPa and 90 °C. Precipitation may augment more degradation of flow transport in time.

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A combined technology of shallow stabilization and floating-type cement treated columns has been developed as method with acceptable settlement for maintaining the function of the high standard roads or high embankments on soft ground. So it is important to predict settlement of this type improved ground. In this study, a composite spring model for predicting the total settlement of this type improved ground is proposed with consideration of settlement reduction effect in relation with improved parameters such as improvement ratio and improved depth. Coefficient of volume compressibity of the improved portion and total settlement are derived by this proposed model. Its validity is confirmed from the one-dimensional consolidation tests and loading model tests with the plane strain conditions.

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Comparing with clay, as the compressibility of peat is extremely high and consolidation coefficient c_v is strongly dependent on consolidation stress, it is difficult in many cases to apply Terzaghi consolidation theory which is based on the assumption of constant c_v and without taking into account of the change of initial thickness of consolidation layer. In this paper, the possibility of accurate prediction of the horizontal deformation as well as the vertical settlement of a deep peaty soft ground loaded by test embankment with vacuum preconsolidation is investigated by using soil-water coupled elasto-plastic finite element (FE) analysis which takes into account of consolidation stress dependency of c_v and effects of geometrical changes of deforming soil body. A series of simulation analysis was also performed by changing the combination of the magnitude of negative pressure and filling rate to investigate the possibility of establishing the optimum design procedure for this particular ground improving method.

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To predict the long term elasto-plastic behavior of unsaturated earth structures, the constitutive model, which can express the following typical behavior of unsaturated soil, is needed. One is shrinkage and stiffness increase due to suction increase, second one is collapse with stiffness decrease due to suction decrease, and the last one is the influences of suction history relating to the hysteresis of soil-water retention characteristics. In this study, a constitutive model of unsaturated soil applied the effective degree of saturation as parameter expressing stiffness was proposed. The model showed good agreement with the experimental results and the appropriateness of the model was demonstrated.

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Three kind of marine clays with various plasticity and silica sand were mixed at different proportions, and specimens were prepared either by water sedimentation or by pre-consolidation. Then, a series of consolidation and undrained shear tests were performed on the specimens. Thus, soil samples with broad grain size distribution, i.e. ranging from sand to clay, were formed and, based on the test results, a unified method to evaluate the undrained shear strength of sand-clay mixtures was proposed. When the fines content is low, a soil mixture is formed such that the sand particles form the soil matrix while the finer particles occupy the void spaces in between. The strength of the soil mixture is dependent on the void ratio formed by the sand matrix. On the other hand, when the fines content is increased up to a certain point, the fines dominate the matrix structure of the soil, with the coarse sand particles scattered around, resulting in the strength of the mixture being controlled by the characteristics of the finer particles.

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A new in-situ permeability test of determining soil hydraulic properties in the near surface of unsaturated sandy soils is proposed. The constant head infiltration test and the gravity drainage test were performed continuously. The transient soil water content during these tests were measured by a portable soil moisture device. The inverse solution of unsaturated soil hydraulic functions was applied to independently measured transient water content data for wetting and drying process to consider hysteretsis phenomenon of unsaturated soil hydraulic properties. The utility of our proposed method is demonstrated by using numerical models and experimental data of unsaturated dune sands.

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This study shows how the calcium carbonate content of sediments can influence the sedimentology. Since the origin of calcium carbonate in marine sediments is marine organic remains, such as coccolithophore and foraminifera, the ratio of carbonate and total materials in mass base depends on the rate of terrigenous materials discharged from land. Therefore, the carbonate content is reflected by sedimentary conditions which include the distance from land or river mouth, and sea level. It follows that marine sediments always contain calcium carbonate of a certain concentration, while sediments under freshwater usually contain little carbonate. Thus, marine sediments are distinguished from non-marine sediments by carbonate content. In addition, calcium carbonate content of sediments is available in assessing stratigraphical division.

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Kobe Airport has been constructing offshore from Kobe Port, and Holocene clay layer distributes sickly at its zone. As it was necessary to grasp how much Holocene clay layer consolidated, the soil survey before constructing and the measurement of soil behavior by the various gauges has been made in reclaiming from the sea in order to solve its property. As a result, it was revealed that alluvium clay was quasi-over-consolidated and its degree is high at western and northwestern zone. Moreover, the value measured at field was more than value analyzed by laboratory test results and the void ratio of soil after consolidated was smaller than laboratory test result. On this property, it was necessary to lessen over-consolidation ratio. After the analyzed value was reviewed, it was roughly correspond to the value measured at field and the validity of reviewing was confirmed.

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During the 1964 Niigata earthquake, the left bank of Shinano River moved several meters towards the river center because of lateral spreading caused by liquefaction. To explore evidence of lateral spreading, the authors have conducted an in-situ soil investigation at the left upstream riverside of the Showa Bridge using a pile-type sampler called the Geoslicer. The method enabled us to visualize the detailed soil pro.les. From the observation of peeled slice, typical stratum structure of liquefaction such as the dike of fluidized sand, water escape structures and disturbed horizontally sedimentation stratum, which is overlaying the lique.ed sand layer, were found. Using the sand sample, we have also studied physical and mechanical properties of soils.

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Numerical model for mass transfer in gas-phase of soil is very important to simulate the movement of volatile liquid like chlorinated organic solvent and organic oil, etc. Then, results of the study for mass transfer in gas-phase of soil have been reviewed and concluded in this paper. Then, mass transfer equations with multi-components which can simulate mass transfer effectively and accurately, have been derived from results of study until now in this report.

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