Development of a numerical method and proposal of design method for structures in discontinuous rock

点击翻译按钮获取中文摘要

In order to realize safe and economic design and construction of rock structures, it is necessary to develop an analysis method that can accurately predict the behavior of rock mass during excavation. In the present study, MBC (Micromechanics Based Continuum) model is developed. In MBC model jointed rock mass is replaced with an equivalent continuum body whose constitutive equation is obtained from the relationship of the average stress and average strain over a representative volume element. To derive the average strain, the displacement jump along a joint is evaluated. The derived constitutive relationship directly reflects the orientation and spacing of the dominant joints and presents strong induced anisotropy.First, analysis of the cavern excavation for Shiobara power station is carried out and the results of the analysis are compared with real data. It is shown that the developed method captures the complicated behaviors of the rock mass during large-scale cavern excavation.For the present numerical method to be adopted in the design, its input data must be determined from geological survey and in-situ test. A method to determine the input parameters for the MBC model from measured convergence during tunnel excavation is proposed.A design method of deep tunnel for nuclear waste disposal is proposed based on the proposed MBC model. It is demonstrated that the thickness of tunnel lining is determined rationally for given joint orientation and density according to the proposed design method.