含一组贯通节理岩体强度的各向异性分析

Analysis of strength anisotropy of rock mass with a set of persistent joints

节理岩体是一种连续和非连续介质共存的地质体,其强度具有显著的各向异性,为了研究岩体强度的各向异性特征,基于能统一处理连续和非连续问题的数值流形方法(NMM),编制弹塑性NMM计算程序,并对不同应力状态下,节理倾角和节理间距不同的岩体压缩试验进行数值模拟.计算结果表明:当节理倾角较小岩体不沿节理滑移破坏时,岩体强度仍会受到节理的削弱而降低;岩体强度-节理倾角曲线呈现出非对称的"勺形";岩体强度随节理间距变化曲线符合负指数函数变化规律;节理间距对岩体强度的影响具有各向异性;岩体强度的各向异性随着围压增大而减弱.通过对数值计算结果进行回归分析,基于新的节理分布参数,提出适用于含一组贯通节理岩体的强度预测模型.该模型综合考虑了节理倾角、节理间距和围压对岩体强度的影响,可更好地为地下工程提供技术支持.

Jointed rock mass is a kind of geologic body containing both continuum and discontinuum,which leads to its strength significant anisotropic.The numerical manifold method （NMM） can solve the continuous and discontinuous problems in a unified way.Based on the elastoplastic program of NMM,the compression tests of rock mass with different joint inclination and joint spacing under different stress state were simulated.The results show that the strength of rock mass with small joint inclination is lower than that of intact rock,even through the rock mass does not slip along the joint.The curve of rock mass strength-joint inclination is shaped like a spoon with asymmetrical sides.The variation of rock mass strength with joint spacing conforms to the rule of negative exponential function.The effect of joint spacing is significant anisotropic.The anisotropy of rock mass strength decreases with the increase of confining pressure.Based on the regression analysis of simulation results,a new joint distribution parameter was proposed,and then a new strength prediction model was established for the rock mass with a set of persistent joints.In this model,the effects of joint inclination,joint spacing and confining pressure are comprehensively considered.It can provide good technical support for underground engineering.