围压卸载下高应力岩石动力扰动的破坏特性(英文)

Failure characteristics of high stress rock induced by impact disturbance under confining pressure unloading

利用改造后的动?静组合加载SHPB装置,系统研究砂岩预先经三维加载再围压卸载的动?静组合加载的破坏特性。结果表明:采用动?静组合加载,当动载荷较大时,试样整体失稳,应力—应变曲线为典型的I型曲线;随着动载荷的减小,应力—应变曲线逐渐向II型曲线转变,即向岩爆曲线过渡,揭示了高应力下动力扰动诱发岩爆,释放弹性储能的现象。使用高速摄像仪拍摄试样破坏过程,直观反映试样的动态破坏过程。剥落碎片的断口表面形貌特征分析显示,用较低能量冲击时,试样受到张剪性破坏和膨胀性破坏的共同作用;当用较高能量冲击时,试样以膨胀破坏为主。碎块分形结果表明,采用高应力动?静组合加载,当用小能量冲击时,引发弹性储能释放能提高试样的破碎程度。

The failure characteristics under coupled static and dynamic loading were investigated by the improved split Hopkinson pressure bar （SHPB） with axial pre-pressure and confining pressure. The results show that the stress—strain curve of the rock under static-dynamic coupled loading is a typical class I curve when the dynamic load is comparatively high; With the decrease of the dynamic load, the stress—strain curve transforms to a typical class II curve. The dynamic failure process was recorded by high-speed photography. Analyses of fracture surface morphology show that the failure modes of specimens are tensile failure or combined shear failure when the impact load energy is low, but the failure modes of specimens become tensile failure when the impact load energy is high. The results of fractal dimension show that the elastic potential energy release leads to increase in the degree of crushing of samples when the energy of impact load is low under coupled static and dynamic loads with high stress.