冲击载荷下岩石压胀对其性质的影响

Influences of dilatancy on rock properties under shock loading

采用落锤动态加载岩石实验系统,通过调节落锤质量、下落距离及活塞杆垫板材料,记录岩石瞬间形成冲击压力脉冲,研究压胀对不同岩石性质影响的规律。实验结果表明,压胀产生后岩石的性质发生了改变,岩石的渗透率有不同程度的增加,且岩石越致密,渗透率增加倍数越大;岩石的弹性模量和弹性极限随岩石体积的增加而降低;压胀产生后纵波和横波在岩石中的传播速度减小,岩样内部产生了微裂纹或原有微裂纹延伸扩展造成孔隙度增加。

Drop-hammer load experiments were performed on different rock samples.By changing the drop hammer weight,drop height and piston rod spacer material,transient shock pressure pulses in the rock samples were recorded by the pressure gauges.Experimental results indicate that the properties of the rocks undergo the following changes induced by dilatancy：（1）the permeability of the rocks increases in varying degrees,and the denser the rock is,the greater the increase multiple of the permeability is;（2）the elastic modulus and elastic limit decrease with the increase of rock volume;（3）the propagation velocities of longitudinal and transverse waves decrease in the rocks;（4）the porosities in the rocks increase due to the extension of the new-produced or inherent micro-cracks in the rocks.