A new concept of Newmark's sliding block method for predicting permanent displacements of earth slopes subjected to seismic loading is presented. Horizontal ground acceleration is used as input motion to move a rigid circular sliding block inside an embankment. The effect of the maximum ground horizontal acceleration, velocity and displacement; the maximum value of the response spectrum of the earthquakes for acceleration, velocity and displacement, the values of the response spectrum corresponding to the maximum permanent displacement; and spectrum intensity as well as predominant frequency of the earthquake acceleration on the permanent displacement are studied.

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This paper presents the results of measurements in subway line vibration by ballast mat. These measurements were performed at ground level line and subway line like subway rail, rail support, wall, ceiling, column and ballast mat. The vibration reduction characteristics and the difference of spectrum property in ground level line and subway line were provided. Finally, an estimation methd of vibration reduction by these countermeasures was presented, being based on insertion loss theory.

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It is generally said that mountain tunnels are little damaged by earthquakes. However, recent case studies of the damage of maintain tunnels caused by earthquakes also show that they are likely to be damaged when 1) the scale of earthquake is large, 2) there are earthquake faults near the tunnel or 3) there are special conditions. We collected infatuation on the tunnels which suffered damage from earthquakes, and performed field surveys of the tunnels damaged by the 1995 Hyogoken Nanbu Earthquake to study the damage mechanism of mountain tunnels. We analyzed the collected data, classified damage patterns and preformed simulation analyses and model tests. Based on the study results, we concluded that we can classify damage patterns of mountain tunnels by earthquakes into the following three patterns; 1) damage of tunnel entrance, 2) damage of tunnel at the fracture zone, 3) damage by sliding of faults. We can prove these mechanisms by the results of simulation analyses and model tests.

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Two kinds of specimens of non-plastic silt were prepared by different methods (the one, tamping and the other, air-pluviation) to investigate the liquefaction and post-liquefaction characteristics. The former was intended to simulate artificially-made fills, and the latter was to reproduce pluviation of deposits. These specimens were used in cyclic triaxial tests to make clear liquefaction and post-liquefaction characteristics of non-plastic silt. A special attention was paid to post-liquefaction permanent deformation. Based on the results from cyclic triaxial tests, a modeling was made for formulation of post-cyclic shear strain taking into consideration the degradation characteristics in modulus of deformation after cyclic loading history.

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This paper describes a method to evaluate the conditions of tunnel face stability in sand strata that contain a clay layers by model tests and numerical analyses. Experimental results show that soft clay strata make the collapse range wider and the position of soft clay stratum determines the range and magnitude of ground damage. These phenomena can satisfactorily be simulated by the two-dimensional rigid plastic finite element method. Parametric studies prove that the internal pressure required to stablize the tunnel face depends on the strength, position and thickness of the clay stratum. The method is proved to be equivalent to that with ground improvement by using the Mohr-Coulomb failure hypothesis. Then, the conditions of face stability can be obtained by the cohesion c, angle of internal friction φ for sand strata and cohesion c for clay strata.

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To find a simple method for predicting the post-earthquake settlement of clay layer, the settlement characteristics in the recompression stage following the undrained cyclic shear were observed. Tested samples were kaoline and reconstituted marine clays. In conclusion, 1) the smaller the plasticity index of clay, the larger the decrease in effective stress during the cyclic shear and also the larger settlement during the recompression stage was observed, 2) when the amplitude of cyclic shear strain is small, the settlement-time relations are similar to those for the over consolidated clay, 3) the apparent earthquake-induced subsidence in the alluvial clay layer in the Port Island, Kobe, Japan, was observed.

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We authors investigated the effects of mechanical properties of gravel and gravel content to the mechanical properties of gravelly rock, using boring-cores from breccia-type andesite and tuff breccia, Neogene Volcanic gravelly rocks in Hokuriku district, which have relatively lower contrast in mechanical properties between gravel and matrix. The result are follow:
(1) No relationship was recognized between gravel content measured around core sample and mechanical properties of rock as qu, E50 and modulus of dynamic elasiticity.
(2) As for the mode of rock failure, in a little case the stress concentration effect was recognized at the boundary between gravel and matrix. But, in most of cases, we were not able to recognize the stress concentration effect between them.

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We authors made a few types of artificial gravelly rock, which had relatively lower contrast in mechanical properties between gravel and matrix. similar to one of breccia-type andesite and tuff breccia from Neogene volcanic gravelly rocks in Hokuriku district. We used the unconfined compression test. and investigated the relationships between gravel content and mechanical properties of them. As the result of this investigation, for example. larger the gravel content, smaller the uni-axial strength, the failure strain and the limit strain. These are different from the result about the natural gravelly rocks mentioned above, which have no relationship between gravel content and mechanical properties of rocks for example uni-axial strength. It might suggest the necessity of investigation not only about gravel content but about another factors from the natural gravelly rocks.

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In Japan, the incinerated ash of municipal solid waste (MSW) was disposed into controlled-type landfill. In this paper, the authors conducted the unconfined tests, oedometer tests and permeability tests using acompacted samples which experienced different curing time from 0 to 180 days. (1) In case of being compacted at disposed moisture content (43%), unconfined compression strength showed increasing tendency up to a value of 1, 300kN/m² at 180 curing days. (2) Coefficient of permeability decreased from 1×10^-5cm/sec at non curing day to 1×10^-8cm/sec at 180 days. (3) Compression index Cc was 0.3 for the sample with no curing days. But it lowered gradually down to a value of 0.1 as curing time passed to 180 days.

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In this research the deformation characteristics and load transfer behavior of a piled raft in the elasto-plastic ground are studied using soil-water coupled deformation analysis. The plane strain piled raft is simulated introducing some linear constraint conditions over the velocity field. The piled raft reduces the final settlement significantly. This reduction is due to the load transfer through shear by piles into deeper soil layers which disperses the induced stresses compared with only the raft. The settlement of a piled raft is not affected by the permiability of ground. Further, the piled raft induces homogeneous settlement even with eccentric loading, however, this is not effective for a ground with an inclined bed rock.

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In this paper, the mechanical response of rock mass to high-pressure hydraulic injections applied during hot dry rock (HDR) stimulation is studied. The sliding of natural joints originated by the action of water pressure is assumed to be the governing mechanism of hydraulic fracturing. The constitutive relationship for the mechanical behavior of jointed rock mass under hydraulic fracturing is formulated by the extension of the MBC (micromechanics based continuum) model which is developed for mechanical behavior of jointed rock mass under excavation. Numerical simulation of hydaulic fracturing injection at Hijiori, Japan is conducted. The numerical results are in agreement with experimental data.

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This paper employed the numerical procedure based on the lower bound theorem by introducing the contact condition along rock joint to clarify the mechanical property of joint strength. By simplifying the complicated real geometry of rock joint, the effect of triangle shape asperity on joint strength was investigated. The applicability of employed method was examined in comparison with both the experiments by Patton and the upper bound solutions by limit analysis. The failure mechanism of rock joint was shown to change with the increasing normal stress from the sliding failure along the asperity to the mixed failure of sliding along the asperity and shearing of asperity. It was found that the non-linearity in joint shear strength for normal stress was caused by the change in failure mechanism of rock joint.

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The stress-strain relationship for unsaturated soil is discussed in this paper. Based on the Karube's theory, two types of the suction stress are used, and a new concept on the plastic yield condition and hardening parameter is proposed. The stresses used are called bulk stress pb and meniscus stress pm. Effects of pore water composition for mechanical behavior are presented by using two types of suction stress. As a result, constitutive model is derived by associated flow rule is proposed. Using the derived equations, triaxial compression test and consolidation test with suction change are simulated. The calculation results simulate two types of the test data well.

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This paper presents a soil/water coupled formulation for unsaturated soil mass as an initial-boundary value problem, in which the constitutive equation for unsaturated soils proposed by Karube et al. is employed. This model is characterized in terms of bulk stress and meniscus stress. And also the water retention curve plays an important role to specify their inner stress components in the theoretical formulation of constitutive modeling. A soil/water finite element code is examined throughout comparison with some analytical solutions. Finally, in this paper, the F. E. code is applied to an initial-boundary value problem and the stress/deformation developing inside the domain is examined. The importance of considering mechanical characteristics of unsaturated soils is emphasized in the case of analysis of soil structures such as the core of rock fill dam.

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Lateral resistance, failure mechanism, plastic processes, and horizontal subgrade reaction etc. were investigated through a laboratory experiment on a laterally loaded single pile in clayey slope. On the basis of the observed results, a 3D plastic analysis model was proposed to calculate the horizontal subgrade reaction force in a sloped ground. Using this model, the relation between lateral displacement of pile and horizontal force was examined, and it was shown that the calculated relation was in well agreement with the experimental result.

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Two large water supply pipelines collapsed at Osaka in 1997 and at Kyoto in 1998. Investigation on the site conditions and collapsed structures of cast iron pipes in both cases suggested that the reaction forces against the earth pressures acting along the longitudinal axes of the pipelines concentrated onto particular supporting points of the pipelines. Centrifuge model tests and FE elastic analysis revealed that the longitudinal deformation of the pipelines increased the circumferential deformation of the pipelines at the supporting points, and this interaction between the longitudinal and circumferential response was the critical factor to cause the collapse of the pipelines.

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In this article, some representative analysis methods for a jointed rock mass are employed as the method that can accurately reproduce the mechanical behavior of the jointed rock mass. The excavation of the Shiobara power station cavern constructed by the Tokyo Electric Power Company is analyzed by them, and results, such as a relative displacement at cavern wall as a function of time and a displacement distribution of rock mass, are compared with measurement data. Based on the numerical results, the constitutive low of each method is considered by paying attention to the mechanical behavior of the jointed rock mass obtained from each analysis, and the mechanism which gives rise to the distinctive behavior of the rock mass is discussed. Furthermore, a point common to all and a point of difference are clarified by the results, and their distinctive features and different points in terms of the mechanical behavior of the jointed rock mass during the excavation of large-scale cavern are disputed.

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In Japan, there are a lot of construction results of power -station cavern. It is, however, indispensable to develop the analysis method which is able to predict the behavior of rock mass during cavern excavation so as to make an excavation under the condition of severe geology and earth pressure. In this article, the Nonlinear Analysis Program Including Softening Model, the Micromechanics-Based Continuum Model, the Equivalent Rock-bolt Model, the Multiple Yield Model, Crack Tensor Model and Damage Tensor Model are employed to carry on the analysis of cavern excavation. First, their macroscopic equivalent shear modulus are compared under the condition that a macroscopic material includes a single discontinuity. Next, the input parameters by which the behavior of rock mass during the excavation of the Shiobara power station constructed by Tokyo Electricity Power Company is reproduced are extracted. Using them, one element problem is analyzed by those models, and their results are discussed.

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This paper proposes an innovative back analysis method to model out inhomogeneous behaviors, which is suitable for cavern excavation in rock masses with a loosened or fractured zone. This method allows us to estimate the extent and characteristics of inhomogeneous zones with iterations, defining the reduction factor of elastic modules by strain outputs and following the back analysis formulation to take initial stress parameters as well as non elastic strains as unknowns with minimum norm solution. It is applied to the numerical experiments and also the actual cavern construction problem and the results suggest that more reasonable strain distributions with proper reduction factors can be appropriately estimated in a reasonable calculation time.

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This paper describes results of test road including ten kinds of different types of pavement on soft clay ground. The purpose is to find a reasonable method for pavement on a highly compressive clay ground, where engineers often encounter a big differential settlement between the pavement and pile-supported structure such as a box culvert. Based on the observed settlements, final settlements of each pavements are predicted. Construction costs and the maintenance costs are estimated to evaluate the total costs. Discussion based on these costs leads to a conclusion that the total cost could be the lowest for a high grade pavement compared with a conventional low grade pavement.

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In the analysis of slope stability in discontinuous rock, it is very important to simplify the way needed for finding out a dangerous block in three-dimensional analysis. There exists a stability evaluation method by which the blocks which needed to be evaluated are picked up among numerous blocks. In this paper, a simple stability evaluation method is proposed by formulating a failure condition of the rock, taking into consideration the wedge effect and the location of the discontinuous plane. By comparing the results obtained from the proposed method with those from stereographic analysis, it is shown that the proposed method is effective in identifying the dangerous block.

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This study deals with described the experimental results concerning rheology characteristics of the liquefied sand specimen which was measured by a viscometer using tuning-folk vibration mechanism. The specimen was kept in the liquefied sand condition by upward infiltration flow during measurements, and the behaviors of flow curves measured were changed by flow rate from pseudo-plastic fluid like to Newton fluid like as the flow rate increased. Furthermore, the behaviors which could be considered Newton fluid or Bingham fluid were shown as we focused on the shear strain rate area less than 0.2 (1/s). As a conclusion, it became clear that the coefficients of viscosity in these results depended on the shear strain rate, namely the flow curves had the characteristics of pseudo-plastic fluid. From these results, the equation to obtain the coefficient of viscosity which was dependent on shear strain rate and flow rate as pseudo-plastic fluid was derived.

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The predictions of groundwater level around a dam which varies in the both space and time domain is very important for the dam maintenance. Geostatistical space-time models have been applied for modeling such spatiotemporal distributions in several scientific disciplines. In this paper, the new spatiotemporal random model and space-time cokriging are proposed. The model is characterized by the non-stationary as the random model in the temporal domain varies in the space domain. For the purpose of verifying its availability, the proposed method is applied to the data of an actual dam, consequently, it has proved to be very effective tool for estimation of spatio-temporal groundwater behavior through the some examinations.

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