岩石Ⅰ型动态断裂的围压效应数值分析

Numerical analysis of confining pressure effect on rock I mode crack dynamic fracture

摘要: 为探究围压对岩石I型动态断裂过程的影响，以页岩直切槽半圆盘弯曲试样为研究对象，利用数值分析方法开展了含有围压条件的分离式霍普金森压杆试验，分析在不同冲击荷载的作用下围压对岩石裂纹扩展速度及断裂韧性的影响。研究结果表明：围压会限制岩石I型裂纹的萌发与发育，并提高岩石的断裂抗阻性。在冲击荷载应力波幅值325～375 MPa之间，每增加2 MPa的围压，初始裂纹的萌发时间延后3～6 μs，裂纹扩展速度减小5.5%～20%，断裂韧性增大1.01～1.05倍，冲击荷载越大裂纹扩展速度受到围压的影响越显著、断裂韧性受到围压的影响越小。

Abstract: To explore the confining pressure(CP)effect on the I-mode crack dynamic fracture process of rock,the split Hopkinson pressure bar test with CP was carried out by numerical analysis method with shale notch semi-circular bending specimen as the research object.The influence of CP on crack propagation velocity and fracture toughness was analyzed.The results show that CP will limit crack development and improve fracture resistance.When the impact stress wave amplitude is between 325～375 MPa,the initial crack generation is delayed by 3～6 μs,the crack propagation velocities are reduced by 5.5%～20%,and the fracture toughness is increased by 1.01～ 1.05 times for every 2 MPa increase in CP.