冲击荷载作用下岩石裂纹扩展的机理分析与FD-PDM数值模拟

本项目围绕动载条件下岩石裂纹扩展特性，采用冲击压缩实验研究和有限差分-近场动力学法(FD-PDM)耦合数值模拟，探讨岩石裂纹扩展规律及动力学机理。首先，基于50mm杆径的SHPB试验平台，开展含不同长度、倾角、数目的预制裂纹岩石冲击压缩试验。利用超动态应变仪记录岩石试样应变信号，借助高速摄像机实时观测裂纹扩展过程，分析裂纹长度、倾角、数目对裂纹扩展的影响。对破坏后的试样进行开裂面局部切片电镜扫描，从微观上得到岩石裂纹扩展模式分类，揭示扩展的动力学机制。其次，通过改善近场动力学法数值频散性质，建立FD-PDM耦合算法，对岩石裂纹扩展进行高效模拟。本项目将岩石裂纹扩展特性的研究扩展到更高应变率段，可为强扰动(岩爆或爆破)条件下的岩体破坏特性研究提供重要理论依据和高效数值算法。

This project is focus on the rock crack propagation characteristics under impact loading. Impact compression experiments, as well as FD-PDM (Peridynamics method coupled with finite-difference method) simulation are carried out in order to investigate crack propagation law and dynamic mechanism in rocks containing pre-cracking. First, based on a 50 mm diameter SHPB test platform, impact compression tests of rock specimens containing pre-existing cracks with different lengths, dip angles, and numbers are conducted. The strain signals of rock specimen are recorded by super-dynamic strain gauge, and the crack propagation process is observed in real time using high-speed camera. The effects of crack length, dip angle and number on crack propagation are analyzed. The cracked surface of the damaged specimen will be scanned using scanning electron microscope (SEM), and the crack propagation patterns will be classified microscopically, to reveal the dynamic mechanism of the crack propagation. Secondly, via improving the numerical dispersion properties of Peridynamics, a coupling algorithm of FDM and PDM is established to perform highly efficient simulation of rock crack propagation. In this project, the research of rock crack propagation characteristics is extended from low strain rate to a higher strain rate, which can provide important theoretical basis and high-efficiency numerical algorithm for the study of rock failure characteristics under strong disturbance (rock burst or blasting) conditions.