节理粗糙度对应力波传播及试样破坏影响的颗粒流模拟

为了研究节理粗糙度对应力波传播规律的影响以及粗糙节理试样受应力波作用发生破坏的微观机理,利用基于离散元方法的数值分析软件PFC2D构建了SHPB系统的颗粒流数值模型.在已有SHPB物理试验的基础上对试验中采用的节理试样进行微观参数标定,研究了较低冲击荷载下节理粗糙度对应力波传播的影响规律以及较高冲击荷载下不同形貌节理试...

Particle Flow Simulation on Influence of Joint Roughness Coefficient on Stress Wave Propagation and Specimens Failure

In order to study the effect of joint roughness coefficient（JRC） on stress wave propagation and the mechanism of failure of rough joint rock specimens under stress wave action，a numerical model of particle flow code in a split Hopkinson pressure bar（SHPB） system was established by using PFC^2D，a numerical analysis software based on discrete element method. Based on the existing SHPB physical test，the microcosmic parameters of joint rock specimens were demarcated. By comparing the waveforms of incidence，transmission and reflection generated by physical test and numerical simulation，the microscopic parameters were adjusted until the waveforms were basically the same，so that the correctness of the numerical model was verified. The numerical model was used to study the influence of JRC on stress wave propagation under low impact load and the microcosmic crack propagation and failure mechanism of joint rock specimens with different morphology under high impact load. In addition，the stress balance at both ends of the specimen under low impact load was analyzed by using the stress balance factor and the stress variation with time at the incident end and transmission end of the specimen. The typical stages of stress change at both ends of joint rock specimen and complete specimen in numerical impact test were compared and analyzed to explain the delayed effect of stress wave on joint surface and the effect of joint roughness on the increase of stress at the incident end. The results show that the presence of joint surface can reduce the transmission coefficient of stress wave，and the larger the JRC value of joint rock specimen is，the smaller the transmission coefficient is，and the stronger the reflected wave of the joint surface is，the more obvious the effect of stress growth slowing down at the incident end of the specimen is. Under impact load，the crack initiation occurs at the joint surface and spread rapidly to the whole part of the specimen，especially the end surface of the specimen，most of the cracks are formed in the post-peak stage，and tensile cracks are dominant. The rougher the joint surface is，the lower the dynamic strength is，the more easily the specimen is destroyed and the more cracks are produced.