对层状岩体使用修正的Hoek-Brown破坏准则的有限元分析

FEM analyses for layered rock mass using modified Hoek-Brown failure criterion

针对用于各向异性岩石材料的修正后的Hoek-Brown准则,推导相应的数值计算格式,将其引入可对横观各向同性介质进行弹塑性分析的二维有限元程序中,以一个假定的位于层状岩体中的矩形地下洞室为算例,通过改变岩体层面的倾角,计算和分析围岩中的位移、应力及塑性区。结果表明:当岩体层面的方向位于某些角度时,围岩中可能无或出现范围不同的塑性区,层状岩体各向异性的变形和强度特性对洞室围岩的力学动态及稳定性具有强烈的影响。

Aiming at the Hoek-Brown failure criterion which can be used for an anisotropic rock material, the alterative form for numerical computation is derived, and this form is introduced a 2D FEM code for elasto-plastic analysis of transversely isotropic medium. Taking an assumed rectangular underground cave in a layered rock mass as the computation background, the displacements, the stresses and the plastic zones in the surrounding rock mass are analyzed numerically through changing the dip angle of the bedding surface of rock mass. The results show that the orientation of the bedding surface of rock mass is limited in some angle range, the plastic zones can or cannot occur in the surrounding rock mass, so the anisotropic characteristics of deform and strength of layered rock mass have strong influences on the mechanical state and the stability of surrounding rock mass of a cave.