The authors are analyzed the large-scale structure build on the discontinuous rock foundation by earthquake response analysis with non-linear FEM considering the rock joint system using the actual earthquake record. The earthquake response analysis was performed by equivalent continuum finite element method as Multiple Yield Model (MYM) introducing cyclic loading elastic-plastic deformation characteristics of rock joints, and the analytical results were compared with the observed earthquake response. As a result, adequate modeling of discontinuities and appropriate setting of mechanical properties of rock and discontinuities give the good results corresponding with the observations. We confirmed the applicability of MYM to earthquake response.
The present situation in waste plasterboard disposal looks bleak due to a shift to the controlled disposal of waste plasterboard, an increase in the amount of discharged waste plasterboard, and other factors. To reduce the volume of waste plasterboard disposal, this paper investigates utilization in subgrade soil of bassanite reproduced from waste plasterboard. CBR tests of sands compacted with both 0-40% bassanite and 5% blast furnace slag cement (B type) were carried out. Optimum water content increased with increasing bassanite/soil (B/S) ratio. Maximum dry density fell at B/S ratio of 40%, but increased up to B/S ratio of 20%. The CBR value was the maximum at the optimum water content, at all B/S ratios. The CBR values at the optimum water content increased with increasing B/S ratio. Consequently, addition of a large volume of recycled bassanite to ground can create lightweight ground with large CBR values.
The authors have proposed a method to evaluate uncertainty involved in spatial variability of geotechnical parameters and resulting statistical estimation error in geotechnical reliability analysis. The soil profile is model by a stationary random field, which is simplification and idealization of the real ground. In the proposed method it was assumed that the effect of spatial variation of geotechnical parameters on the performance of a geotechnical structure can be evaluated by considering the local average over a certain appropriate range of ground. The validity of this approximation method is examined in this paper by taking several typical geotechnical structures as examples. The exact solutions by MCS and those by the approximation method are compared to examine the validity of the method.
The authors have proposed a basic framework and a method to evaluate uncertainty involved in spatial variability of geotechnical parameters and resulting statistical estimation error in geotechnical reliability analysis. The soil profile is model by a stationary random field, which is simplification and idealization of the real ground. The local average at an arbitrary point in the random field is estimated from limited samples obtained from the same filed. The two estimation methods are proposed, namely the general estimation and the local estimation The relative positions of samplings and of the structures are not considered in the former, whereas they are considered in the latter. The theory is merely idealization and simplification of the real problem. The theory is verified based on intensive cone penetration tests at three sites. The method is basically cross verification which compares the estimated estimation variance with calculated true values based on the intensive CPT measurements.
When it is raining the main reasons of the soil failure are thought to be the increase of soil weight ingenerated by rainfall infiltration, the decrease in shear strength, and the increase in infiltration by the rise of ground water. Today the evacuation signal systems are developed in case of danger and the signals are announced according to the rainfall index. These systems are useful though still have weaknesses in accuracy. By understanding the rainfall intensity, infiltration, and deformation characteristic of the foothold would contribute to the improvement of this system. In this paper, model test has been conducted using weathered granitic soil, to measure the negative pore water pressure, deformation, and ground water level. Using these three measurements the consideration on the mechanism of the slopes instable process has been done. Also the consideration on the application properties of the results of the model test has been done, using the data achieved from the in-site measurement. As a result, behavior of unsaturated seepage around the basic layer is important to calculate the surface failure and to assume the escape limit during rainfall.
One of the methods for measuring and evaluating stability for tunnels and structures around tunnels is use of the critical strain method. Critical strain is defined as elastic strain of axial strain. At the beginning in this study, I describe an evaluation method of critical strain of rocks proposed by Sakurai. The uniaxial compression test and uniaxial tension test were carried out using five kinds of rocks and the failure mechanism is examined. Finally, a new evaluation method for critical strain of rocks is proposed. In addition, the critical strain method proposed by Sakurai is compared with the evaluation method proposed in this study. Critical strain of proposed method in this study and Critical strain of Sakurai method are almost equal. The results of examining the effects of anisotropy, water and confined pressure on the critical strain are also described.
The evaluation of the advection-dispersion in the fracture and diffusion into the matrix from fracture is very important to describe the mass transport processes in fractured porous media such as a sedimentary rock. However, it is often difficult to uniquely determine a number of parameters relevant to the advection-dispersion and matrix diffusion phenomena, such as the fracture aperture, dispersivity coefficient, and matrix diffusion coefficient, from a data set of single tracer test. In this report, the uniqueness of the parameter estimations from one-dimensional tracer test was studied using an analytical solution for single fracture model. And the new method of tracer test conditioning to uniquely estimate these three parameters was suggested.
The stability of slopes where ground anchors (hereinafter anchors) are embedded is appraised by loadcell to measure the load, and observing how the changes in the tensioning force settle down. But loadcells measurements sometimes do not indicate a constant value even when the loadcells are setting on stable ground. In addition, checking the function of a loadcells and to set loadcells to working anchors are extremely difficult. Currently, the practical method of anchor monitoring is not established. In this paper, we will report on the characteristics of loadcells based on data of loadcells placed on multiple anchors. And we developed the method of desorbing loadcells on anchors, and proposed the method of monitoring of residual anchor load.