高静载条件下受频繁动力扰动时蛇纹岩动力学特性研究

Dynamic characteristics of serpentinite under condition of high static load and frequent dynamic disturbance

基于改进的分离式霍普金森压杆(SHPB)岩石动静组合加载试验系统,进行了在不同静力轴压条件下受频繁动力扰动作用的动力学试验,研究蛇纹岩在高静载下受频繁冲击扰动过程中的动态变形特性、动态峰值应力和应变、能量变化规律和岩石破坏模式等动力学特性。研究结果表明:高静载条件下受频繁冲击扰动作用时,在动态峰值应力前,动态应力与应变呈正相关关系,而在动态峰值应力后,出现变形回弹和不回弹两种现象;随着动力扰动次数的增加,岩石动态峰值应力减小、动态峰值应变增大、动态变形模量减小、岩石由释放能量向吸收能量方向转化;随着预加静力轴压的增大,单次冲击过程中岩石损伤加剧,岩石破坏需要的扰动冲击次数减少,同时岩石由拉伸破坏模式向压剪破坏模式转变,破坏块度由小变大、均匀度降低。试验结果对揭示深部岩体承受高地应力和频繁开挖爆破等动力扰动作用下的破坏机制具有重要意义,同时为工程实际中通过调整围岩静应力状态和爆破以提高围岩长期稳定性的可行性提供了室内试验支持。

Based on the improved split Hopkinson pressure bar（SHPB） testing system with the rock coupled static and dynamic loads, dynamic experiments on serpentinite are conducted under the condition of different static axial compressions and frequent dynamic disturbance to research its dynamic deformation properties, dynamic peak stress and strain, energy variation and failure modes. The results show that in the process of frequent disturbance under the high static load, there is a positive correlation between the dynamic stress and strain of rock prior to the peak dynamic stress, but there are two different dynamic deformation phenomena, i.e. dynamic deformation rebound and non-rebound after the peak dynamic stress. With the increase of number of dynamic disturbance, the peak dynamic strain increases while the dynamic peak stress and the dynamic deformation modulus decrease, and the energy variation of rock changes from the release of energy from rock into the absorption of energy from dynamic disturbance. As the static axial compression is larger, the damage of rock during one impact disturbance is heavier, the impact disturbance number for rock failure is fewer, the failure mode of rock transfers from the tensile failure mode to the shear failure mode, and the fragmentation distribution of broken rock becomes more inhomogeneous, and fragments become larger. All these results will be helpful for us to reveal the failure mechanisms of deep rock mass under the high static stress and dynamic disturbance produced by frequent excavation and blasting, and prove the feasibility of adjusting static stress state and excavation blasting to maintain the long-term stability of surrounding rock in field site.