一种确定双重孔隙介质黏聚力与内摩擦角的方法及其有限元分析

对于双重孔隙-裂隙介质岩体,考虑裂隙对孔隙基质强度的弱化作用,提出了一种确定此种岩体表征单元中任一平面上黏聚力N c及内摩擦角N?的方法,通过本方法得到计算结果与Attewell法所得岩体强度各向异性变化曲线基本一致,证明了所建立的N c,N?值计算式是合理的.将上述求N c,N?的方法引入所研制的二维弹塑性有限元程序中,针对岩体中不同裂隙状态的一个矩形地下洞室,对3种不同工况进行计算与分析,结果显示:随着裂隙组数的增加,岩体的黏聚力和内摩擦角减小,围岩中应力、位移的量值及分布发生明显变化,且塑性区的面积非线性急剧增长.

A method for determining cohesion and internal friction angle of dual-pore-fracture medium and the relative FEM analyses

For dual-pore-fracture rock mass, by considering the effect of facture weakening, a method for determining the cohesion CN and internal friction angle φN of arbitrary plane in a representative element was suggested. It was proven to be reasonable for the coordination of the anisotropy variation curves of rock mass strength obtained by this and Attewell＇s methods. Introducing the method for the solving of CN and φN into the elastic-plastic FEM code developed by the authors, aimed at a rectangular underground cave, three cases with different fracture states were computed. The results show that with the increasing of fracture set number, the cohesion and internal friction angle of rock mass and the plasticity zone decreased and sharply, nonlinearly grew respectively, and the magnitude and distribution of stress and displacement in the surrounding rock mass changed obviously.