岩体侧向卸载变形破裂PFC^(2D)数值模拟

PFC^(2D) Numerical Simulation for Deformation and Fracture of Rock Mass Side-discharging

为探讨岩体在侧向卸载作用下的变形破裂行为,采用PFC2D离散颗粒流软件再现了岩体在侧向卸载作用下的失稳破坏过程。通过相似材料岩体室内单轴压缩试验来获得岩体在PFC2D计算所需各参数,然后以此为基础进行岩体的侧向卸载变形破裂数值模拟试验。结果表明:侧向卸载作用下岩体破坏以2条相互贯通的共轭张剪主裂纹为主,其裂纹发展可分为5个阶段;卸载岩体变形表现为沿卸荷方向的强烈扩容或膨胀,最终岩体的3个岩块将沿主裂纹面发生相互错动;岩体的扩容量与卸载速率成指数衰减关系,且卸载速率越大,卸载岩体的脆性特征就越明显,其破坏具有突发性、猛烈性和复杂性。

To investigate deformation and fracture behavior of rock mass under the action of side-discharging,unstable failure process under the action of side-discharging is reproduced by using discrete granular flow software of PFC2 D. Firstly,the parameters of rock mass for PFC2 Dcalculation are obtained by uniaxial compression test of rock similar material,and then based on it,numerical simulation test of deformation and fracture under the action of side-discharging is conducted. Research results show that the main failure behavior of rock mass presents as two conjugated tension-shear main fractures which are interrelated under the action of side-discharging. Crack expansion can be divided into five stages. Rock deformation of side-discharging shows strong dilatation or swelling in the direction of side-discharging. Finally,three blocks of rock mass will occur mutual diastrophism along the main fractures plane. The volume expansion value of rock mass shows exponential decreased relation with unloading rate,and the faster the unloading rate is,the more obvious the brittle characteristics are,which is burstiness,violent and complexity.