动静组合加载下含孔洞层状砂岩破坏机制探究

Research on failure mechanism of stratified sandstone with pre-cracked hole under combined static-dynamic loads

为揭示层理岩石在动静组合加载条件下的力学特性及破坏模式机制,采用分离式霍普金森压杆装置对层状黄砂岩试样施加一维动静组合载荷,结合数字图像相关技术,实时监测试样的动态破裂过程,并分析不同倾角下岩石的破裂演化过程及能耗特性。研究结果表明:动静组合荷载作用下,随层理倾角的增大,含孔洞层状黄砂岩试样的动态强度总体上呈现出先增大后减小的变化规律;不同层理倾角含孔砂岩试样的破坏模式存在明显差异并可被归纳为4类;层理角度为45°时,岩石强度最高,吸收能占比最大。在深部地层的冲击破岩中,合理布置冲击荷载与层理方向间夹角以及破岩位置,可有效提高破岩效率,减小动力扰动对围岩带来的不利影响,提高深部岩石工程的稳定性。

To reveal the mechanical characteristics and failure modes of stratified rock under combined static-dynamic loads,a split Hopkinson pressure bar device was used to apply one-dimensional load on stratified sandstone specimens.Meanwhile,digital image correlation technique was used to monitor the fracturing process in real time.Fracture evolution and energy consumption characteristics of different dip angles were further summarized.The results show that:under the combined static-dynamic loads,the dynamic strength of stratified sandstone specimens with holes initially increases and then decreases with the increase of bedding angle.The failure modes of the specimens can be divided into four types.The energy consumption characteristics of different dip angles under combined loads show that when the bedding dip angle is 45°,the strength of sandstone specimens and the proportion of absorbed energy reach the maximum values.In underground engineering,reasonable arrangement of breaking position and the angle between the direction of impact load and bedding can significantly improve the efficiency of rock burst,reduce the adverse impact of dynamic disturbance on surrounding rock,and enhance the stability of deep rock engineering.