非贯通节理岩体损伤变量计算方法研究

作为岩体组成部分的非贯通节理对岩体力学特性有着重要影响，然而几乎目前所有的岩体损伤变量计算方法都仅考虑节理几何参数对岩体力学特性的影响。对含单组非贯通节理的岩体力学特性进行研究，提出一个能够同时考虑节理几何及强度参数对岩体力学特性影响的新的岩体损伤变量计算方法。首先，采用弹性余能等效假设代替Lemaitre应变等效假设研究由节理引起的岩体各向异性损伤，并基于断裂力学中单个节理引起的附加应变能增量与损伤力学应变能释放量相关联的观点，推导出由单条节理引起的损伤变量计算公式。其次，根据断裂力学理论获得了单轴压缩下单条节理尖端应力强度因子（SIF）KⅠ、KⅡ的计算公式。最后，通过考虑节理间的相互作用给出了单组单排或多排节理尖端应力强度因子KⅠ、KⅡ的计算公式，得到了单组节理引起的岩体损伤变量计算公式，并与已有试验结果的对比分析证明了该公式的合理性。

A method for calculating damage variable of rock mass with non-persistent joints

As part of the rock mass, the non-persistent joints inherently affect the rock mass mechanical behavior. Nearly most of the existing calculation methods of the rock mass damage variable can only consider the influence of the joint geometrical property on its mechanical behavior. Therefore, this study focuses on the mechanical behavior of the rock mass with a set of non-persistent joints in order to propose a new calculation method of the rock mass damage variable which can both consider the influence of the joint geometrical and mechanical properties on the rock mass mechanical behavior. First, the hypothesis of elastic complementary energy equivalence is adopted to replace the Lemaitre strain equivalence hypothesis in order to study the anisotropic damage of the rock mass induced by the joints. And based on the connection of the increment of additional strain energy caused by the existence of one joint in fracture mechanics and the emission of damaged strain energy in damage mechanics, the calculation formula of the rock mass damage variable caused by one joint is deduced. Second, the calculation formula of the stress intensity factor(SIF) KⅠ and KⅡ of a single joint tip under uniaxial compression is studied according to the fracture mechanics theory. Third, the calculation formula of SIF KⅠ and KⅡ of a set of one or more-rowed joint tips is given by considering the interaction among the joints. Finally, the calculation formula of the rock mass damage variable caused by a set of non-persistent joints is obtained; and then its validity is verified by the existing test results.