Abstract

In deep buried rock engineering, in situ stress is a significant factor affecting the mechanical response of rocks to dynamic loads. This work focuses on the effect of confining pressure on dynamic deformation of rocks. Considering the limitation of observation in laboratory experiments, numerical simulation method is adopted. The numerical model of split Hopkinson pressure bar test system with confining pressure is established in a two-dimensional particle flow code. Dynamic compression tests of sandstone under different confining pressure conditions are then simulated. The axial dynamic compressive deformation, crack evolution, failure modes and dynamic dilation of specimen are obtained. The results indicate that confining pressure has a constraint influence on both axial and transverse deformation of rock. Under the compression of confining pressure, the axial dynamic deformation, and damage degree are weakened while the elasticity of rock may be enhanced. Compared with that without confining pressure, the failure modes of rock specimens are different under the confining pressure. Dynamic dilation of rock specimen is triggered synchronously with the crack initiation. Confining pressure can weaken the dilation, and contraction of rocks may even happen after the dynamic unloading under a high confining pressure, resulting in a secondary damage to rocks. The results can benefit to comprehend the dynamic deformation and failure of deep buried rocks.

摘要

在深埋岩石工程中，原位应力是影响岩石对动态载荷的力学响应的重要因素。这项工作的重点是围压对岩石动态变形的影响。考虑到实验室实验观察的局限性，采用数值模拟方法。在二维粒子流代码中建立了具有围压的分裂Hopkinson压力棒试验系统的数值模型。然后模拟了不同围压条件下砂岩的动态压缩试验。获得了试件的轴向动态压缩变形、裂纹演化、破坏模式和动态膨胀。结果表明，围压对岩石的轴向变形和横向变形均有约束作用。在围压压缩下，轴向动变形，破坏程度减弱，岩石弹性增强。与无围压相比，围压下岩石试件的破坏模式不同。岩石试样的动态膨胀与裂纹萌生同步触发。围压会削弱膨胀作用，在高围压下动卸荷后甚至会发生岩石收缩，对岩石造成二次破坏。研究结果有助于理解深埋岩石的动态变形和破坏。岩石试样的动态膨胀与裂纹萌生同步触发。围压会削弱膨胀作用，在高围压下动卸荷后甚至会发生岩石收缩，对岩石造成二次破坏。研究结果有助于理解深埋岩石的动态变形和破坏。岩石试样的动态膨胀与裂纹萌生同步触发。围压会削弱膨胀作用，在高围压下动卸荷后甚至会发生岩石收缩，对岩石造成二次破坏。研究结果有助于理解深埋岩石的动态变形和破坏。