斜入射波扰动对岩石层裂的影响

Effect of oblique incident wave perturbation on rock spalling:An insight from DEM modelling

为了研究应力波斜入射作用下岩石的层裂特征,采用颗粒流程序(PFC)模拟了霍普金森压杆(SHPB)层裂试验。选用的试样斜截面角度分别为30°,45°和60°,分析了在5.2 m/s,5.6 m/s和6.2 m/s冲击速度下斜入射波对岩石层裂破坏的影响,并与90°截面试样进行比较。结果表明,当斜截面角度大于45°时,应力波遇斜截面直接反射成拉伸波,且拉伸波与压缩波交替出现,一旦反射拉伸波超过试样某一位置的抗拉强度,试样在该处发生拉伸破坏。当斜截面角度小于45°时,反射波在斜截面内与入射波多次叠加,诱使试样斜截面先发生层裂。此外,基于纵波传播理论,还推导了30°斜截面的应力函数,得出斜截面可能发生层裂的位置,与模拟结果吻合良好。

In order to study spalling failure characteristics of rock under oblique incidence of stress wave,a split Hopkinson pressure bar(SHPB)spalling test with a special shaped striker was simulated by Particle Flow Code(PFC).The oblique section angles selected in this study were 30°,45°and 60°,respectively.The spalling failure characteristics of rock with oblique incidence of stress waves at 5.2 m/s,5.6 m/s and 6.2 m/s impact levels were analyzed and compared with those for 90°section incidence.The results show that when the angle of the oblique section greater than 45°,the stress wave will be directly reflected into a tensile wave when it encounters the oblique section,and then the reflected tensile waves and compressive waves will alternately appear.When the angle of the oblique section is less than 45°,the reflected stress wave is superimposed multiple times with the incident stress wave in the oblique section,and induces the spalling of the oblique section.Based on the longitudinal wave propagation theory,the function of stress in the 30°oblique section has been derived.The possible fracture position of the oblique section is obtained,which is consistent with the simulation results.