脆性硬岩CWFS强度准则模型等效塑性参数优化研究

EQUIVALENT PLASTIC PARAMETERS OPTIMIZATION RESEARCH ON CWFS FAILURE CRITERION MODEL OF BRITTLE HARD ROCK

为探究适应脆性硬岩加载破坏的强度准则,以杏山铁矿混合花岗岩为对象,根据室内试验获得岩石物理力学参数及岩样切片扫描图,基于颗粒流理论和PFC程序建立混合花岗岩颗粒细观几何模型,采用Fish语言编制加载命令流并调整相应函数,对岩石单轴和三轴(3=40 MPa)刚性加载试验进行模拟。通过岩石全应力–应变试验与模拟曲线、AE声发射与裂纹监测成果等综合比较研究,获得荷载作用下混合花岗岩细观力学特性及微宏观破裂演化规律。在此基础上,结合岩石单轴刚性加载试验曲线,裂纹数、摩擦力能量与轴向应变关系曲线,以及FLAC模拟,对脆性硬岩黏聚力弱化–摩擦力强化(CWFS)强度准则模型参数进行优化研究与验证。获得杏山铁矿混合花岗岩CWFS强度准则模型参数:初始黏聚力为23 MPa,残余黏聚力为4.3 MPa,初始摩擦角为0°,残余摩擦角为46.3°,临界塑性应变cp,pf分别为0.001 5,0.003 7。该研究成果对杏山铁矿露天转地下开采围岩体破坏机制和力学本构关系研究和工程稳定性分析等具有重要的意义。

It takes migmatitic granite of Xingshan iron mine as the object to study the failure criterion of brittle hard rock. According to the physical and mechanical parameters from laboratory experiments and grains section scanning, micro-geometric model of migmatitic granite grains were built based on particle flow theory and PFC programs, loading codes were developed and some functions were adjusted by Fish language to simulate uniaxial and triaxial（ty3 = 40 MPa） compression experiments. Based on comprehensive comparison and analysis of the complete stress-strain curves, acoustic emission and ＂crack＂ monitoring results fi-om laboratory and simulation, the micro-mechanical characteristics and the cracks revolution laws from microcosm to macrocosm of migmatitic granite were obtained. On this condition, cohesion weakening and fi＇iction strengthening（CWFS） failure criterion model parameters of brittle hard rock were optimized and verified through laboratory curves of unixial rigid loading, relation curves between cracks and fi＇iction energy with plastic strain, and FLAC simulation. The optimized CWFS model parameters of initial cohesion, residual cohesion, initial friction angle, residual friction angle and critical plastic strain e~, ~ ofmigmatitic granite are 23 MPa, 4.3 MPa, 0~, 46.3~, 0.001 5 and0.003 7 respectively, which is of great significance in theory and practice on the study of fracture mechanism, mechanical constitutive relations and engineering stability of rock mass during open pit mining transferring to underground mining in Xingshan iron mine.