Development of Three-dimensional Boundary Element Program for Advanced Designs in Rock Engineeirng and Its Application to Actual Problems.

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Before this research takes effect, Kuriyama and Mizuta has developed a numerical code for three dimensional elastic analysis by the Displacement Discontinuity Method and studied the applicability of it. This 3D-DDM analysis has a distinctive feature that it is effective in modeling of discontinuous plane such as fault/crack which is not easy to be modeled by the other methods, but it is disadvantageous in modeling of free surface of rock. Hence, we developed the numerical code for three dimensional elastic analysis by the Fictitious Stress Method, which is usually used in modeling of the surface of the earth or surface plane of underground opening, by an unique procedure. In this procedure, as numerical integration is not used and analytical integration is used in calculation of influence coefficients among the triangular leaf elements which construct the boundary plane, accurate solutions can be obtained and its computation speed is relatively high.This computation code was combined w … More ith the 3D-DDM code and the computation code for transient analysis of fluid flow in the fracture.On the other hand, we carried out an in-situ hydraulic fracturing experiment assisted by abrasive water jet borehole slotting in the Mozumi Mine of Kamioka Mining and Smelting Co.Ltd.in Gifu Prefecture by different Grant-in Aid. We carried out the tests of fluid injection into the fracture which was produced by hydrofracturing and measured the variations of fluid pressure distribution and surface displacement of the side wall of the drift, which was caused by opening of the fracture. Therefore, simulations of the fluid injection tests were carried out by using the computing system mentioned above and it was confirmed that the computed results with the measured results.A numerical code for three dimensional non-steady heat conduction by the Boundary Element Method was developed. In this program, influence coefficients are obtained through the numerical integration taking the scheme newly developed by us into consideration because the basic formula dealt in the problem can not be integrated analytically and some singularity happens even in the popular method for numerical integration. However, in case of heat conduction analysis, accuracy is sufficient even by numerical integration if the special method is introduced and it was confirmed by comparison of a computed result with the corresponding strict solution. Finally, the program was combined into the combined DDM-FSM-FEM analysis in order to take rock expansion/shrinkage due to hear movement and heat transfer from rock to fluid into consideration. Less