Contamination problems in soil and groundwater are major rising problems in many places. In this paper, oil contamination is the focus and how to quantitatively estimate the hydraulic characteristics of water, gas and oil (3-phase liquid) in porous material is discussed. Laboratory experiments were carried out using a simplified method based on the Green-Ampt model and a complex method based on the instantaneous profile method by using gamma rays. A comparison of the results determined from both methods was discussed. The limitation of the Green-Ampt method in nearly saturated conditions is also mentioned.

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The need of the refinement of the design methodology for belled pile has come to be acknowledged in association with the increase in natural disasters and the liberalization of electric power industry in recent years. Despite the recent development of the computational method for geotechnical problems, it is problematic to find the effective numerical tools readily applicable to the uplift problems of belled pile. We conduct several numerical analyses of the uplift problems to assess the practical applicability of the numerical approach to such problems. Nonlinear elasto-plastic finite element method is utilized to capture the progressive and localized failure in foundation, and the performance of this approach is illustrated through the comparison of the analysis results with the conventional engineering approach based on the so-called logarithmic spiral equation and with centrifugal model experiments.

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To investigate the attenuation under a clear ground condition, this paper describes the development of a centrifugal model test system, simulating the subway-induced vibration, experimental results, and comparisons between experimental observations and field measurements. It was found that the attenuation of subway-induced vibration in the ground becomes larger as frequency becomes higher. Bornitz’s formula is applied to estimate the attenuation and it was found that the values of material damping coefficient α are almost the same in the centrifuge acceleration level of 15 to 62.5G, which are consistent under 70Hz with those obtained by field measurements at 14 sites in and around the Tokyo area.

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Uniaxial compression tests, Brazilian tests, freeze-thaw tests and frost heaving tests were carried out for several saturated rocks under the temperature between -30°C and 20°C. Changes in mechanical properties and deformation behaviors were analyzed paying attention to the behavior of pore water. As the result, strengths increased due to temperature decrease except Inada granite. Two welded tuffs were fractured by the unfrozen water pressure. Frost heaving ability of Shirahama sandstone and Horonobe mudstone was confirmed. Furthermore, ratio of strength increase was correlated with specific surface area or unfrozen water content as well as porosity. The mechanisms of strength increase were discussed, taking deformation behavior for each rock into consideration.

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In this study, column tests were conducted for various sandy soil samples using NaCl solution. An inverse problem study was made to examine test specifications and evaluation methods and the effects of soil conditions on geoenvironmental parameters. As a result, it was found that 1) the effective porosity of samples with high fine particle content was dependent on the hydraulic gradient and the effective porosity of samples with high cation exchange capacity was dependent on electrolyte concentration, that 2) the longitudinal dispersion length of samples with high fine particle content was much greater than the values in existing literature, and that 3) sufficiently accurate geoenvironmental parameters could be identified using a simple formula as long as a Peclet number of more than 40 could be secured in the column test.

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A FOD (Fiber Optic Doppler) sensor that can measure AE (Acoustic Emission) has been invented and developed. The measuring principle is completely different from that of the conventional PZT type AE sensor. The FOD sensor is made by looping a optical fiber and it is glued on object to measure vibration. It measures the vibration as the frequency changes of laser light due to the Doppler effect. The FOD sensor has the following advantages; (1) small diameter and small weight, (2) immunity from the electromagnetic noises, (3) durability and corrosive resistance, (4) usability under high temperature, (5) long-range transmission, and (6) low cost. In order to examine applicability of the FOD sensor to monitoring of rock structures, the authors compared the sensitivity and the frequency response of the FOD sensor to those of the convertional PZT type sensor in laboratory experiments. The results indicated that the FOD sensor has strong possibility to be used for real rock structures.

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The frame of a triaxial specimen was established by measuring the three-dimensional coordinate in the images obtained using two methods. In the “8 Cameras” Method, 8 digital still cameras were used. In the “Rotated Specimen” Method, only one camera was used and all surfaces of a specimen were captured by rotating it. The accuracy of the coordinate measurement was 0.05mm in both methods. In order to analyze the shear band in a drained triaxial test, the details of the shear band was extracted by the three-dimensional coordinates measured in all surfaces of the specimen and the continuous change of the void ratio in the shear band was estimated. The results revealed that the void ratio of the shear band in Toyoura sand exceeded the maximum void ratio in the residual stress state. Moreover, in the post-peak stress state, the shear band of Masado was observed to form with decreasing thickness.

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In this paper, numerical analysis method is proposed to simulate tensile resistance behaviour of reinforced stabilized soil with geogrid. New models of stabilized soil or geogrid are developed for finite element method implemented with particle discretization. Laboratory test result that examined the influence of the amount of stabilizer and the confinig pressure was simulated. It is shown that the proposal method has applicability in the evaluation of the effect of the improvement.

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The present study aims at revealing mechanical behavior of anisotropic ground beneath a structure subjected to cyclic loading. In particular, effect of fabric anisotropy on cyclic strength-lateral flow deformation behavior was investigated by using the soil box apparatus. For example, dependence of fabric anisotropy of the ground on deformation direction was evaluated quantitatively. Test results showed that deformation direction in the ground-structure system depended strongly on the depositional condition of the ground and developed in the direction of bedding plane where the relative angle δ=45°-φ/2-ψ became the smallest in the ground.

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Earthquake and rain induced rapid and long-traveling landslides can cause heavy damage and are very difficult to escape from. Prevention by e.g. installing drainage systems, anchoring the slopes is difficult. Thus it is important to evaluate the landslide risk with help of run-out analyses.
In this study, a new and practical depth averaged method for landslide run-out analysis across three-dimensional terrain by discretizing St. Venant’s equation with MPM was developed and results of run-out analyses of elastic material, dry sand and recent rapid and long-traveling landslides are presented.

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In order to understand the mechanical and permeable properties of rock masses for construction of underground structures, shear-flow coupling tests of specimens having a single rock joint were performed under constant normal stiffness conditions. In the tests, how the permeable properties depend on various physical parameters, such as normal stress, joint surface roughness and hydraulic gradient, were examined. The results show the relationship between the mechanical and permeable properties of rock joints in relation to pore structures created by surface roughness under shear process.

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A series of vertical and horizontal loading tests were conducted on the existing piles constructed in Hokkaido, in order to evaluate the bearing capacity and deformation characteristics of piles in volcanic ash grounds. Static cone penetration tests were also performed at the same sites. From test results, the skin friction f of piles in the welded pyroclastic fall deposit tends to decrease compared with that of sandy soil. A correlation was between the cone point resistance q_t and skin friction f. It was also indicated from CCP and SPP tests that the normalized coefficient of horizontal subgrade reaction could be estimate from the pile deformation at the ground surface.

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In this study, we performed the box shear test and the cyclic tri-axial test in order to make clear the mechanism of slope failures due to rainfalls after the earthquake. As a result, the cohesion of the soil decreased by the cyclic loading and the degree of saturation rising with the submergence. These mean that the soil shear strength was decreased because the skeletal structure of the soil was destroyed by the seismic motion and decreasing of the shear strength was generated additionally by increasing of the degree of saturation due to the rainfall after the earthquake. This is one of mechanism that many slope failures occurred by rainfalls after the Kobe earthquake.

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This paper reports the results of laboratory permeability measurements of fault rocks and their host rocks obtained from the Median Tectonic Line in Ohshika-mura, Nagano Prefecture, central Japan, by using a gas-medium apparatus under confining pressure at dry conditions, with nitrogen as the pore fluid. Most samples from the incohesive zone under hydrostatic pressure have a permeability ranging between 10^-13 to 10^-17 m², which are greater than those of cemented cataclasites and mylonites by more than 2 orders of magnitude at all effective pressures up to 180 MPa. Permeability measurements of fault gouge and cemented cataclacite specimens during triaxial compression tests revealed marked effects of deformation on the permeability, and the effects of these rocks were very different from each other. Thus, fault permeability structure is heterogeneous and anisotoropic, and may change abruptly prior to or during fault activities and during the inactive priod.

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Contaminant transport is one of the important issues to assess geoenvironment. The groundwater is the most important transport media. Therefore, effective porosity and flow dimension related to groundwater flow are key parameters to evaluate the contaminant transport. We propose new method to estimate these parameters by using single hole injection test with high viscosity fluid. In the theoretical part of this paper, we derive the flow equations of high viscosity fluid under both constant flux injection and constant pressure injection for arbitrary dimensions. Standard curve are derived theoretically. Based on these standard curves, we illustrate parameter estimation procedure using graphical method of superposition. Using this method, we can estimate flow dimension, effective porosity and extent of flow zone related to groundwater flow.

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The various physical and mechanical laboratory tests were taken to the crushed stones and the gravel soil for revealing the property of reclaimed ground at Kobe Airport. On considering the high compressibility by the ground submerged and the particle breakage which occurred by reclaimed works, the maximum and minimum densities were set up. The specimens of the same relative density with in-situ condition were made and the laboratory tests were taken to them. Within the specified these samples, the larger fine contents was, the higher density became and the smaller liquefaction resistance became. The shear resistance angles of all specimen were larger than 37°.

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To manage and treat huge number of roadside slopes, simple evaluation method of slope stability is required. In this paper, a method for evaluation of discontinuous rock slope is proposed. Main features of this method are as follows; 1)stability of triangular pyramid and wedge shaped blocks can be evaluated; 2)three modes of failure, i.e. rockslide , rockfall and toppling are taken into account; 3)stability analysis is based on limit equilibrium theory; 4)friction angle, cohesion and tensile strength of joints are taken into account; 5)pore-water pressure and seismic force can be applied to the block; 6)conditions of stability of blocks are evaluated with simplified vector formulas.

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This study aims at revealing characteristics of particle breakage for volcanic coarse-grained soils mainly formed from pumice particles. In order to examine changes in void structure due to particle breakage, a series of the creep test using triaxial apparatus was performed on two kinds of volcanic coarse-grained soil with different crushability. An estimation method of void structure for volcanic soils was proposed based on a void model. Test results showed that existence of both inter-particle void and intra-particle void was clearly observed in the volcanic soils, especially the amount of the intra-particle voids had an influence on the creep behavior. It was also indicated that the particle breakage characteristic depended strongly on intra-particle void ratio with the opening, thereafter the closing intra-particle void ratio decreased with the progress of creep.

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Air-foam treated lightweight soil which is a mixture of clay, cement and air foam has been utilized in coastal areas. Its construction results are extending because we can expect its high performance for weight, strength and stiffness. However, it is recently pointed out that the lightweight soil can be significantly damaged under inappropriate circumstances. This paper summarizes 10-year follow up study of the lightweight soils placed in backfill of seawall in both Kobe Port Island and Tokyo International Airport. It was confirmed that the physical and mechanical properties of the lightweight soil were maintained their required performances, indicating that the lightweight soil has sufficient durability as a geo-material.

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A method to evaluate permanent deformation of an embankment and a slope is proposed, in which spatial distribution of shear strength and amplification characteristics of the earthquake motion in the embankment/slope are considered. This method is composed of two procedures to evaluate a critical slip surface and permanent deformation. A method is proposed to evaluate critical slip surface of multi-layered embankment as logarithm spiral shape. The Newmark's method is improved in order to consider the effect of amplification of the earthquake motion in the embankment by employing the energy principle; the conventional Newmark's method is expressed to be a case with rigid body motion of the sliding mass. The method is applied to the slope failure of the river dike of the Naruse river, Kimasuka district during the 2003 Northern Miyagi Prefecture earthquake and good agreement is obtained with the observed damage.

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A bearing capacity of vertically loaded steel steet piles was investigated in the present paper. Although sheet piles have been widely used for several kinds of the structures and so required to resistance against the axial loads in these days, a bearing capacity of them has not been sufficiently studied so far.
The bearing capacity of steel sheet piles was investigated by full-scale field load tests and a series of small model tests, where the failure patterns of the model ground around the vertically loaded sheet piles were visualized and investigated with X-ray computed tomography (CT) scanner. Consequently, the authors have proposed the vertical load-carrying mechanism of steel sheet piles placed in the ground.

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The purpose of this study is proposing for the test method for measuring the hydraulic conductivity of bentonite mixtured soil used as a seal liner of waste disposal site after the construction in situ. Concretely, it is a method for building in the moisture sensor in which the measurement in the pinpoint was possible for Air Entry Permeameter, which exists in situ permeability test method. In results of this study, by catching fall time of wetting front, 10^-8(m/s) order of hydraulic conductivity could be measured in about 10 minutes. And, the validity of this proposed method was verified by carrying out the one-dimensional infiltrating test, and measuring moisture profile and pressure distribution in the test-piece.

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The permeability of the bentonite ground as an engineered barrier is possibly designed to the value which is lower than that determined in terms of required performance because of heterogeneous distribution of permeability in the ground, which might be considerable when the ground is created by the compaction method. The effect of heterogeneity in the ground on the permeability of the bentonite ground should be evaluated by overall permeability of the ground, whereas in practice, the effect is evaluated by the distribution of permeability in the ground. Thus, in this study, overall permeability of the bentonite ground is evaluated from the permeability distribution determined using the geostatistical method with the dry density data as well as permeability data of the undisturbed sample recovered from the bentonite ground. Consequently, it was proved through this study that possibility of overestimation of permeability of the bentonite ground can be reduced if the overall permeability is used.

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