不同的层状岩体抗剪强度表达式计算效果的有限元分析

Finite element analyses of computational effects with of different shear strength expressions for layered rock mass

为考察不同的各向异性抗剪强度表达式对于数值计算结果的影响,以一个假定的位于层状岩体中的矩形地下洞室为背景,分别使用笔者和Pietruszczak各自提出的材料摩擦系数和黏聚力随方向变化的公式,进行3种工况的弹塑性二维有限元模拟,对比了围岩中的应力、位移及塑性区。结果显示,笔者提出的经验表达式与和相应的Pietruszczak一阶表达式在计算中的精度基本相当,而与Pietruszczak的二阶表达式相比有较明显的差别。

In order to investigate the effects of different anisotropic shearing strength expressions on numerical computation results, the two-dimensional elastoplastic finite element analysis were carried out for an assumed rectangular underground cave in a layered rock mass for three cases, in which the empirical formulae for internal friction coefficient and cohesion of material which change with directions suggested by the first author and S. Pietruszczak were applied respectively. The stresses, displacements and plastic zones in the surrounding rock mass are compared. The results show: the computational accuracy of using the empirical expressions established by the first author matches basically with that of using the first-order approximations given by Pietruszczak; but there is a comparatively obvious difference between the computational accuracies of using author’s empirical expressions and Pietruszczak ‘s 2nd order approximations.