The densification process of the loosely deposited sand bed that has once liquefied under oscillating water pressure on its surface is investigated by using the vertically one-dimensional model. In the analysis, the elasto-plasticity of the sand bed skeleton, the sedimentation in the liquefied sand bed and the liquefaction ratio are taken into account. The experimental results verified that the proposed analytical model expressed the dynamical behavior of sand bed through the process from the occurrence of liquefaction to the densification of the sand bed fairly well.

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There are many roadbeds which are insufficient of their quality in existing lines and so the occurrence of mud-pumping together with penetrative settlement causes track irregularity. This is why track maintenance labor has increased. Therefore, this paper elucidates the primary factors of ballast penetrating phenomena and made clear the contribution degree of the factors to the formulas of penetrating settlement. To be more specific, the determination of the causes of ballast penetrating settlement is conducted in indoor tests.
Finally, field surveys are made in a broad area to determine the causes of the phenomena and to confirm the formulas of penetrating settlement.

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A series of undrained triaxial compression tests with controlled strain-rate and strain-acceleration was performed on reconstituted clay. On the basis of the test results, isotach models using irrecoverable strain and its strain rate were developed so as to evaluate time-dependent behaviour of the clay under undrained conditions. Applicability of these isotach models was in depth examined in relation to the undrained be-havoiur of clay subjected to shearing, creep and relaxation.

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This study focuses on grounds with coefficients of permeability of 10^-3cm/s or less in which grouting using ordinary cement is difficult, laboratory mixing tests and grouting tests were conducted on mixture of ultra fine-grained cement and kaolinite clay. Based on these tests, the authors were able to propose mixing proportions appropriate to the actual permeability of the ground. In addition, the authors have leaded an equation for estimating the penetration length of grouting. Furthermore, the method for design of the conditions of grout and pitch of grouting pipes, according to the estimated penetration length of grouting, is proposed.

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Earth pressure on and deformation of drainage pipes buried under high fills with prototype heights up to 100m, measured in a total of 26 centrifuge model tests using five types of model pipes with different flexibihties, were compared well with results computed by FE elastic analysis. The analysis considered the existence of loosened zones inside the trapezoidal dry-sand-backfill area surrounding the model pipes, as well as non-linear deformation behavior of polyethylene model pipes. The analysis explained change in the deformation behavior of the pipes due to pipe flexibility, cover height, fill material, and thickness of fill under the pipe reasonably well. It was concluded, therefore, that this FE method is useful to develop a new design method for drainage pipes buried under high fills.

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Triaxial compressive re-loading testing was conducted under laboratory confining pressures to examine the Kaiser effect on rocks in the different stress state from that of rocks in situ. Two rapidly increasing points of cumulative AE count were to be observed. The two stresses of 1st and 2nd kaiser effect points were then compared with pre-axial stress and pre-differential stress. The estimated axial stress and the estimated differential stress are not influenced by confining pressure. Micro-crack model which generates AE at the secondary crack growth, is a good explanation of the experimental results. This model testing is found to be able to explain the Kaiser effect even under a different confining condition from that of pre-loading.

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The shear strength of a rock joint has been focussed by many engineers over several decades. So far as the authors know, there are many publications concerning the shear test under constant normal load and/or stiffness. In consideration of allowable limit of displacement/deformation associated with rock tunnelling, we should pay more attention to the meaning of the shear behavior of rock joints under constant dilatancy than the one under constant normal load and stiffness, which is much far from the reality in rock tunneling with loosening phenomenon. By employing more than 140 specimens which were reproduced from 20 natural joints with different roughnesses, the authors have carried out direct shear tests under both constant pressures and dilatancies.
The breakage of joint asperity was discussed from the point of view standing on the relationship between the loss of asperity and mobilized shear strength. The change of shear strength from the peak to the residual strength has been clarified and the appropriate installation of supporting elements in rock tunnelling was discussed.

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Through the long term running research conducted by the prime author, it has been clarified that, when seismic wave propagated through rock joints, the change of amplitude showed more sensitive than that of propagating velocity. Basing on this observation, the authors carried out the measurement of the velocity and amplitude of propagating wave during the rock joint shear test. It was confirmed that the monitoring by means of the change of amplitude of propagating wave could show the progress of loosening during excavation. The final objective of the research is to estimate the magnitude of loosening phenomenon in quantitative manner which is essential in rock tunneling.

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This paper proposes a formula widely applicable for calculating bearing capacity of shallow foundations, which can evaluate inclined load action from superstructure and inclined bearing stratum at the same time. The formula is derived using seismic coefficient method and admissible velocity field method. In practice, most bearing capacity formulas assume only influence of load inclination. Then, it was found from the newly proposed formula that in case of strong earthquake level, most of the present formulas might have risk to over-evaluate bearing capacity.

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This paper investigated the mechanism and the degree of the aging effect on marine alluvial clay with a wide range of plasticity. In this study, consolidation paths using a logarithmic compression index Cc to p as well as to f are adopted because of little affectation with Ip. (1) Lower and upper yield points close to p_c are clearly shown. The upper yield points is directly related with the initiation of failure of the soil structure. (2) The development of the aging effect influences fundamental compression shapes, the logarithmic compression index ratio Rc became larger with the increase of effective overburden pressure. (3) Standard compression type specific to Ip exists at critical effective overburden pressure. (4) Fundamental assumptions of Bjerrum's aging effect model are verified.

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Land subsidence of soft ground has been caused by the seasonal fluctuation in ground water level, when it is seasonally pumped up in summer for agricultural purposes such as Saga Plain in Japan. To propose a useful system for preventing the land subsidence due to the seasonal fluctuation in ground water, the results of measurement from the observation well the past 20 years in Saga were used. Based on the observed results, we clarified the relationship between amounts of ground water level fluctuation and pumping of ground water and the residual settlement per year. As a useful parameter of management for preventing the land subsidence, the ground water level withdrawal during pumping was used and its values for some ranks of management were established to each observation well.

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In the construction of NEW-KITAKYUSHU airport, the reclamation by dredged marine clay was performed. In this paper, the predictions at several stages on the reclamation and the effectiveness of modification of prediction with the monitoring are described. The modification is the determination of consolidation parameters so as to fit the calculated change of elevation as well as the distributions of water contents and excess pore pressure with the monitoring data. Use of the best-fit consolidation parameters improves the precision of prediction. The best-fit consolidation parameters are located in the range of consolidation parameters measured on the samples taken from the reclaimed land.

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Mud soil sedimented in a irrigation reservoir generally is high-water-content and very soft clayey soil. Recently, it is necessary to develop the method to make use of such a problematic soil, because there is little space to dispose of it as industrial waste. Therefore, we have developed the embankment method by the cement-stabilized mud soil that can be used to construct a embankment.
In this paper, it represents the results investigated the effects of the physical properties of mud soil on the strength characteristics of the cement-stabilized mud embankment soil by laboratory tests. Based on this results, it is recommended the determined method of design strength and the soil-stabilizer mix design method of the cement-stabilized mud soil, and the quality control method in embankment construction processes.

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Many cut-slopes on the Izumi Belt in Shikoku suffered failure during the construction of Junkando expressway. Based on the orientation of rock bedding planes, these slopes are dealt in two categories: ukeban-rock planes with a reverse angle of dip and nagareban-rock planes with a dipping orientation. The number of failed slopes was greater in the nagareban structure than the ukeban, and most of the failed slopes consisted of medium hard rocks, whereas the slopes with soft rocks and ordinary soil were found stable. These observations interested the authors to investigate the causes of failure and the strength properties of the involved slope materials. As a result, it was found that the angle of friction for the medium hard rocks was comparatively small as they contain expansive clay minerals.

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A series of large-scale laboratory permeability tests have been conducted to clarify the effects of grain size distribution on saturated coefficient of permeability of rockfill dam material. The experimental results show that (1) the saturated coefficient of permeability Ksat of rockfill materials is larger than 1.0×10⁰cm/s for those with D₁₀ in the order of several millimeters; (2) the saturated coefficient of permeability Ksat of the materials is influenced by hydraulic gradient, i for the materials with i between 0.01 and 0.2 and Ksat larger than 1.0×10^-1cm/s; (3) the saturated coefficient of permeability of coarse granular material is affected by not only the value of D₁₀ but also D₆₀

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This study proposes a simple method to evaluate the stability of dam foundation during earthquake in consideration of rock joints. The proposed method consists of evaluation methods for the stability against the failure caused by local shear and global sliding along joint sets in foundation rock for an arch dam. A case study using the existing earthquake analysis result based on continuum model of a typical arch dam is carried out. The results of the case study show that the proposed method is capable to quantitatively evaluate the stability against the shear failure in the foundation rock, the orientations and the shear strength properties of joint sets have significant effects on the shear failure in the foundation rock.

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High capacity micro piles are cast in place and heavily depend on construction technique and soil properties. As such, uncertainties regarding the bearing capacity of the piles are involved. Therefore, utmost care must be taken in designing piles to ensure safety. This paper determines the performance function of a pile's push-in bearing capacity under three separate critical conditions: ground subsidence due to the insufficient bearing capacity of a pile, steel-pipe fractures due to compression, and fractures in non-steel-pipe areas due to compression. We examine these uncertainties in terms of probability and study how to use partial factor design in programming the push-in bearing capacity of high capacity micro piles.

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In this paper, a new sampling device, which is very simple and easy operated, is developed to collect undisturbed samples in a reclaimed ground composed of gravels. By using the samples, drained conventional triaxial compression tests (CD tests) are conducted to investigate the mechanical behavior of the gravels materials. Results obtained from in situ tests such as borehole horizontal loading test, or from the CD tests with remould sample are also compared to investigate the mechanical behavior of gravel materials with different testing methods. Then a real-scale lateral loading test on a 9-pile foundation that was built in the reclaimed ground is simulated with a 3-D finite element analyses based on the experimental data. The validity of the device is confirmed.

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In this study, we propose a method of analysis i. e. VIRTUAL FRACTURE MODEL to predict permeability changes caused by excavating a cavern in anisotropic fractured rock. In this method, based on permeability tensor calculated from in situ tests, fracture settings are virtually created with Bingham distribution. The alterations in permeability of the virtual fracture settings are predicted according to the anisotropic stress changes arround a cavern. This method was applied to predict the permeability changes in Super-Kamiokande excavated in Kamioka Mine at the depth of 1000m. Consequently, both in situ measurements and predictions showed an increase of permeability around caverns to be consistent with each other.

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When constructing underground caverns, it is important to estimate the damaged zone around rock caverns caused by excavation. In situ experiment were conducted to investigate the crack growth into rock mass by acoustic emission (AE) measurement.
The measurement was carried out in Kamaishi mine of Iwate Prefecture. The following conclusions are obtained: (1) AE activities decrease gradually with the time progress after blasting, (2) both tensile cracks and shear cracks occurs intensively around a rock cavern, (3) the damaged zone generated by digging grows up to the wider domain where the excavation has not yet reached, (4) the types of blasting do affect the damaged zone generated.

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In order to evaluate the stability of structure-sand ground system subjected to cyclic loadings such as wave force, a series of FEM analysis based on Mohr-Coulomb formula with non-associated flow rule and model tests were carried out under cyclic and static loading conditions. From test results and analyses, it is found that (1) the deformation behaviors of sand ground subjected to various cyclic loadings can be estimated by the simplified FEM analysis taking account of the dependency of rigidity modulus on stress history and (2) the predicted structure displacements by the proposed method agree well with the results of the model test.

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In this paper, it is examined whether the type of direct shear tests can be applied to highly organic soil to evaluate strength characteristics in the laboratory. A series of shear box tests and ring shear tests are performed on a remolded samples. Based on the test results, strength characteristics of peat soil obtained from direct type shear tests are discussed comparing with those on clay soil. Direct type shear test data are also compared with those by consolidated undrained triaxial tests. It is concluded that direct type shear tests provide more reliable strength parameters on highly organic soil than triaxial or unconfined compression tests. Practical usefulness of the direct type shear test, especially shear box test, is also suggested for the determination of the strength parameters of highly organic soils.

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A series of triaxial compression tests is carried out on the unsaturated silty kaolin clays. Specimens are subjected to undrained compressive shear under the conditions of constant air pressure. The pore water pressure and volume change during shear are monitored. The pore water pressure develops with compression and then turns to decrease with expansion when the degree of saturation is relatively high. On the contrary to it, when the degree of saturation is low, the pore water pressure monotonically increases independent of volume change. These experimental facts can be explained from the effects of the bulk stress. Thus, throughout experimental investigations, it is revealed that the behaviors of unsaturated soils are consistently explained in terms of the meniscus and the bulk stresses. Particularly, it is found that the failure criterion on unsaturated soils can be uniquely described using the suction stress, which is defined as the summation of meniscus and bulk stresses.

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Bifurcation analysis considering variation of aspect ratio was carried out to investigate the influence of soil parameters on bifurcation behavior of normally consolidated cohesive soils under plane strain undrained compression loadings and its application to the prediction of slip surfaces. The soils exhibited plasticity indices of 10, 30, and 50.
The results indicate that bifurcation behavior of the soil with lowest plasticity index occurred at larger stress ratio and smaller axial strain than those with higher plasticity indices. Forms of slip surfaces can be predicted by distribution of maximum shear strain and stress states. We suggest that the soil with lowest plasticity index is brittle. In the case of the soils with higher plasticity indices, failure phenomena arrive from strain localization at slip surfaces through initiation and propagation of shear bands.

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The purpose of this study is to improve the grouting method for fractured rock masses. So experimental study is executed in order to understand the properties of grouting injection and seepage flow in hydraulic fractured aperture. This paper grasps the effect of the properties of grouting stage due to the various conditions such as width of the aperture, viscosity of the grout, water cement ratio and injection flow rate using flat plate fractured model in a laboratory experiment. From the results, it is proposed to select the relationship between the most suitable grout mix (water cement ratio) and width of the aperture to be injected according to the properties of grouting stage.

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The purpose of study is to improve the grouting method for fractured rock masses. In this paper, the result on the fundamental phenomenon for grasping the properties of grouting injection and seepage flow are discussed. The case of grouting stage is studied about the multiple hydraulic fractured apertures in the injected borehole. So the theory on the mechanism is constructed, and experiment is executed in order to verify the availability of the theory. From the result, it is shown that Bernoulli's law is able to prove the behavior of the grouting. And the theoretical evaluation is executed on the experiential procedure of the grouting.

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The GPS displacement monitoring system has been developed to monitor the stability of large slopes by the authors. In this research, the trend model is used for smoothing displacements measured by the system, and the applicability of model is investigated through the field experiments and practical monitoring. It is verified that the trend model is useful for improving the measurement accuracy of the conventional GPS surveying. Methods for predicting the final displacement and the failure time of slopes from continuous monitoring results are proposed, and their applicability is also verified.

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Water was injected into a borehole and generated a crack in a biaxial loaded granite specimen. After that, regarding the crack as a preexisting joint, the maximum loading direction was turned with 90 degree and viscous oil having 80 times larger viscosity than that of water was injected into the borehole. Located sources of acoustic emission indicated that a new crack was generated in the direction normal to the preexisting joint after water remaining in the borehole seeped into the preexisting joint with several small pressure drops. The results clarify the possibility to measure stress state generating a new crack by using viscous fracturing fluid, even in a rock mass having preexisting joints.

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This paper describes the behavior of sandy and clayey ground under lateral loading tests of full-scaled single piles under large deformation. Most of the real structures have rotation-fixed head, whereas there have been few tests of single piles in its consideration. Also, it is difficult to evaluate the ultimate state of a short-length pile, since the behavior is affected by the rotation of the pile bottom. In this study, lateral loading tests of some cast-in-place piles were conducted in sandy and clayey ground. In the tests, a new apparatus was used to deal with the rotation-fixed head. Finally, the differences of the behavior of the piles and ground under large deformation are considered, from the viewpoint of the difference of ground (sand or clay), pile length (short or long), and rotation condition of pile head (free or fixed), based upon the test results.

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Coarse-grained materials containing very large gravels are frequently used. Consequently, it is important to grasp the mechanical characteristics of the materials. However, test method for relative density- having the greatest influence on the strength characteristics, etc. -has not been established. As a result, it is inconvenient for us to make engineering decisions for various phenomena. In this paper, a test method for determining the minimum density of gravelly soils is proposed. The proposed method gave better results than the traditional method. In addition it was easier to carry out the experiments using the proposed method.

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