This paper presents a series of the authors’ trial of (i) estimating the constant volume shear strength of compacted geo-materials based on the concept proposed by Iseda and Mizuno in 1971, (ii) constitutive modelling of geo-materials compacted at the construction sites of large fill-dams, high embankments and highway pavements, (iii) evaluating the pseudo-cohesion proposed by Schlosser and Long in 1973 and (iv) examining the performance of reinforced earth tructuresbyfield testsonlarge-scaled model structures. The trialof estimatingthe strengthof compacted geo-materials is found to be reliable through the tests on the full-scalled trial embankments. Constitutive modelling of compacted geo-materials are successfully carried out for the materials used in two large dams, three high embankments and in highway pavements. It is confirmed through a series of triaxial tests on sand specimens reinforced by placing thin films of aluminum, electrodeposited copper and polycarbonate that the pseudo-cohesion proposed by Schlosser and Long in 1973 does exist exactly in a way they described in their paper. The large-scaled model structures constructed in the field are found to be useful in checking the performance of reinforced earth subjected to static and dynamic loading.

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  This paper proposes a method to detect diffuse-mode bifurcations, which engender localization of deformation with characteristic geometrical patterns in plane-strain sand specimens. The scalar fields of a strain invariant in a two-dimensional domain observed in the specimens are expanded into a double Fourier series, and the Fourier spectra are examined. The methodology proposed is twofold: (1) examination of the spectral intensity to identify the wave number, which corresponds to a possible diffuse bifurcation mode, and (2) investigation of symmetry-breaking process of the deformation via diffuse-mode bifurcations. The proposed method is validated through an application to experimental and numerical results of plane-strain compression test, in which localized deformation and formation of shear bands were observed.

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  This paper discusses the practicability of a three-dimensional groundwater seepage analysis system that uses an extended finite element method (X-FEM). In the groundwater flow analysis for planning and construction of a rock oil tank or a geological disposal repository for radioactive waste, generating meshes in a complex three-dimensional region where numerous strata and underground facilities are modeled requires much time and labor. X-FEM greatly reduces the problem because it can handle material boundaries independent of analysis meshes. This paper proposes a new function for handling material boundaries using X-FEM, and presents the details of formulation. The validity of solutions is shown as compared with conventional methods by conducting numerical tests concerning thin strata such as faults that cause problems in the implementation of X-FEM. Meeting the needs of practical analyses is another objective of the tests. Finally, the direction and rationality of the entire system are described.

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  Paper mill sludge absorbs much water contained in poor soil and stabilizes the soil quickly. Also, even if paper mill sludge is mixed with soils, there is no problem with soil environment. In this study, in order to clarify the influence of the paper mill sludge on stabilization, the poor soils mixed with paper mill sludge are investigated by a series of laboratory tests. The following conclusions are obtained from the present study: (1) The tendency of strength reduction of the soil mixed with paper mill sludge due to adding water fluctuates with changes in the activity of the poor soil. (2) The tendency of strength recovery of the soil by paper mill sludge mixing is fluctuant with changes in the poor soil. (3) If paper mill sludge is mixed with different soil with different activity, the interaction between fibers and soil particles is different.

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  Through the 6 meter high retaining wall test series, the behavior of earth pressures acting on the rigid retaining wall is discussed. The fill materials used were sand and cohesive soil with natural water content. Earth pressures were measured during the filling and the wall yielding stages.
  Test results were evaluated by the working angle of internal friction (φ_wrk) on the sliding plane in Coulomb's wedge, which is derived by the measured resultant force and its inclination on the test wall.
  The compacted backfill of sand shows various phases of earth pressures, i.e. pressures during filling, upon completion of filling, and in active and residual states, while cohesive backfill is likely to behave like friction material and show recovery in terms of earth pressure in an active state. Moreover the derived angle of the sliding plane from φ_wrk effectively explains the position of the actual sliding plane, which determines the influence area of the earth pressure.
  Based on a view of the design earth pressure, evaluation of the working angle of internal friction (φ_wrk) upon fill completion will be practical.

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  During the construction of a shallow overburden tunnel using NATM on soft ground, a phenomenon of equal settlements of the surface, crown and foot of tunnel called an accompanied settlement occurred. FRSP (Foot reinforcement side pile) was utilize to control the ground accompanied settelement and it had been reported that it could prevent ground subsidence effectively. In this study, 2-D elasto-plastic FEM numerical simulation of the shallow overburden tunnel on the soft ground is carried out to discuss the accompanied settlement and the effect of FRSP. In consequent, the FRSP can prevent the ground accompanied settlement with the effect of increasing shear reinforcement, earth pressure when FRSP crosses the shear slide line.

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  It is important to evaluate degree of improvement made by injecting the grouting material. The authors have proposed two techniques to evaluate the grouting effect. One is AE monitoring during grouting operation to clarify a range where the grouting material has permeated into. The other is measurement of P-wave amplitude transmitted between holes before and after grouting. Through the second technique, it can be confirmed that fractures necessary to be improved has been filled with the grouting material. By combining the two techniques, degree of improvement made by grouting can be evaluated with much better reliability than by conventional techniques. In this paper, applicability and reliability of the techniques are discussed through laboratory and in situ experiments.

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  A lot of attention has been paid to methane hydrate (hereinafter referred to as MH) as a hopeful energy resource for the next generation. A series of triaxial compression tests was performed in order to investigate the strength of MH-bearing sand specimens which were formated to simulate a MH bearing sediment in Nankai trough. The tests were done with varying density of host sand, saturation of MH, confining pressure, temperature and pore pressure, respectively. The result revealed that the peak strength of MH-bearing sand increased depending on the density of sand and confining pressure. Moreover, the peak strength increases with increasing the saturation of MH, decreasing the temperature and increasing the pore pressure. Further in the study, K₀ consolidated and drained triaxial compression tests were done on natural MH-bearing sands which were sampled at the MH reservoir in Nankai trough. The strength characteristiccs of the natural samples were similar to that of artificially made samples in the study.

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  The purpose of this study is to investigate the conditions that can be applied the results of the element experiment to the experiment of the practical size. In addition, is to investigate the relation between the water level in the chamber and the density of Toyoura sand irradiated ultrasonic wave. Moreover, Portable Corn Penetration Test was carried out to investigate the relation between the relative density and the strength of Toyoura sand in the chamber. As the result of the experiment, following has been understood. The density of Toyoura sand can be made high density as well as the element experiment. Water level in the chamber does not affect the increase in density of Toyoura sand. There is a good correlation between the relative density and the cone penetration resistance.

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  Reusing drinking water sludge discharged during water purification is anticipated as a good use of waste materials as a geotechnical material. Mixing is certainly effective to improve the amount of supply materials. However, the effects of mixing on environmental economics have not been discussed. Therefore, such mixture must be examined from environmental and economical perspectives. This study defined the environmental value of drinking water sludge, with emphasis on the final disposal amount and the loss of natural soil. The environmental cost was estimated in various mixture conditions. Results show the benefits for geotechnical works of using drinking water sludge alone or decreasing the amount of mixed natural soils.

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  A numerical study is conducted to simulate liquefaction using a microscopic fluid coupling scheme with the two-dimensional Discrete Element Method. The scheme creates triangular fluid cells, which represent void spaces, in a particle assembly by connecting each particle centroid between the nearest three particles. The scheme solves pore water pressure in each void space and fluid flow across them by considering compressibility of fluid caused by particle movement. On the other hand, pore water pressure is applied to particles involved in each fluid cell as a form of body force in proportional to occupied area of each particle in void space. Numerical simulations, in which two types of particle assemblies with different initial porosity are excited by the same acceleration condition as that in a centrifuge model experiment. In the centrifuge experiment, the sand assemblies in a rectangular box is excited by sinusoidal acceleration under loading centrifugal force, which is thirty times larger than the gravity acceleration. The numerical results are compared with those of the experiment. As a result, it is clarified that the scheme represents transient of localized pore water pressure, effective stress and acceleration under dynamic acceleration in saturated particle assemblies with different initial porosity, and is an effective to analyze liquefaction.

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  Ryukyu limestone, which is an organic limestone, is widely distributed over Ryukyu Islands in Japan. In this article, the evaluation of porosity of Ryukyu limestone by the stereology method is given and the results are compared with those from other available methods. Then the effect of porosity on the physical and mechanical properties of Ryukyu limestone under both dry and saturated conditions is described and some empirical relations are proposed and compared with experimental data.

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  In order to examine the influence of void ratio on the collapse of the soil due to rainfall infiltration, suction unloading tests under anisotropic stress condition are implemented for specimens with different voild ratio. Not only loose specimens, but also dense specimens, with smaller void ratio than critical void ratio corresponding to specific suction, are compressed with suction unloading. If the initial void ratio is larger, the compression is also larger. The relationship between the reduction of void ratio and the increase of volumetric water content during suction unloading isn’t enfluenced by initial void ratio.

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  This is a study to conserve the Dunhunag Mogao Grottoes in the arid region of China. The wall paintings in the caves are severely deteriorated by recrystallization of salt that is accumulated by the evaporation of moisture in the rock formation. Our aim is to understand the moisture movement from the Qilian Mountains to the Mogao Grottoes through the observation of the fracture system and vegetations by satellite remote sensing. In this study, Landsat5-TM and Terra-Aster data are used for analyzing geological structures in wide area. The NDVI map, which is analyzed by Quick Bird data, is useful to understand distributions of natural vegetation. In spite of low rainfall locally, significant natural vegetations grow up not only along the river but also on the sand dune and basement rock. We illustrate that some vegetations are distributed on the fracture systems as straight lines in the Sanwei Mountains. These results indicate that moisture moves along the fracture systems and the vegetations absorb it and grow on the fractures. And the results of the fracture distribution analysis in and around the Mogao Grottoes indicate that the major strike of the fractures, the joints and the fissures are the same direction. It is conceivable that moisture moves through the Mingsha Mountains, which have the same geological features as the Sanwei Mountains. And it indicates the possibility that moisture reach to the Mogao Grottoes from the southwest.

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  Diameter-expanded anchor is an anchor which has considerably larger fixed anchor diameter than general anchor. Centrifugal model tests were conducted to comprehend the pullout characterristics of the diameter-expanded anchor. As results, pullout resistance of the diameter-expanded anchor can be separated to the frictional resistance and the bearing resistance and angle of anchor insertion has big inference on pullout resistance were revealed. The calculation technique of ultimate bearing resistance load based on upper bound method was proposed and its validity was verified from the results of centrifugal model tests and full-scale model tests.

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  This paper elucidates drying, saturating, and axial point load strength test methods of smectite-bearing rocks on the basis of analyses of the axial point load strength tests in a forced dry-state at temperatures of 105 ± 3 °C, 80 ± 3 °C, 60 ± 3 °C, and 40 ± 3 °C, respectively and a forced wet-state. The rocks are divided into three groups on the basis of their smectite content. It is to be desired that the axial point load strengths of smectite-bearing rocks are measured the specimens in the forced dry-state, dried in an electric oven at a temperature below 60 ± 3 °C for 4 days or more to achieve a constant mass, and the specimens in the forced wet-state, saturated with water for 15 days or more to achieve constant mass.

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  Because the soil material has a viscous property, the energy consumption required in the process of soil densification depends on the loading ratio. To find the most efficient loading method, which minimize energy consumption within some limited period, the variational method is applied to the time-dependent stress-strain models of soil. Maxwell-Voigit model and Sekiguchi model are chosen as a representative time-dependent model. Also densification tests are conducted at various strain rates in laboratory. The test results show that the Sekiguchi model predicts the soil behavior well, and the parameter of the efficient loading is procured. The proposing loading method based on this model reduces the energy consumption for soil densification.

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  There were the following typos in the article, “Doboku Gakkai Ronbunshuu C Vol.66 (2010) , No.3 pp.564-576”.

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