动力荷载对围压卸载下岩石动态变形模量的影响

利用SHPB岩石动静组合加载实验系统，研究在不同轴压水平下围压以1 MPa/s速率卸载至预加值50%时矽卡岩受频繁冲击作用的动态变形模量变化规律。实验结果表明:高轴压促使岩石内部微裂纹萌发与扩展，降低了岩石抵抗外部冲击的能力。围压的侧向约束阻碍岩石内部裂纹的横向扩展，但在围压卸载时会加剧岩石内部的损伤，这是由于高轴压下，围压卸载导致岩石内部应力重新分布。轴压与围压卸载共同影响着冲击作用下的岩石动态变形模量，通过岩样在冲击荷载下的能量耗散分析岩石动态变形模量的变化规律，有助于了解深部岩体开挖的破坏机制。

Study on dynamic deformation modulus of rock under confining pressure unloading and dynamic loading

Dynamic experiments on skarn were conducted with a modified one-dimensional coupled static and dynamic loads based on SHPB device. The variations of dynamic deformation modulus of skarn under different axial pressures and frequent dynamic disturbance are studied when confining pressure was unloaded at the 1 MPa/s rate to 50% of initial value. The results show that high axial pressure promotes the formation and propagation of microcracks in rocks and reduces the resisting ability under external shocks. The lateral restraint of confining pressure hinders the transverse propagation of cracks inside the rock, but it will aggravate the damage when confining pressure is unloaded. This is because, under high axial pressure, unloading of confining pressure results in redistribution of stress inside rock. The axial pressure and confining unloading pressure affect the dynamic deformation modulus of rock under impact. Base on the variation analysis of dynamic deformation modulus by the energy dissipation of rock under impact, some significant understanding of deep rock excavation failure mechanism are drawn.