基于裂纹界面摩擦滑动演化的岩石断裂研究

Research on rock fracture based on the evolution of friction sliding of crack interface

为了研究压剪应力共同作用下岩石裂纹变形演化机制,开展了压剪作用下含裂纹岩石断裂实验研究,采用数字散斑相关方法作为观测手段,获得了加载过程中岩石表面位移场演化、裂纹界面摩擦滑动演化、裂纹尖端应力强度因子等与岩石断裂扩展对应关系.结果表明:随着岩石表面位移场的演化,裂纹尖端阻碍了位移传递,形成了压应变集中区.随着剪力增加,裂纹上下界面滑动位移经历了无滑移、单调增加和波动增加3个阶段.裂纹扩展及尖端应力分布与裂纹界面摩擦滑动状态密切相关,当裂纹界面处于静摩擦状态时,裂纹尖端应力强度因子变化较小;当裂纹界面处于滑动状态时,裂纹尖端应力强度因子随着裂纹界面局部滑动呈波动增加.

An experimental study on the fracture of cracked rock under the loads of compression and shear was performed for the deformation evolution mechanism of rock crack.The digital speckle method was applied to calculate the displacement field of sample surface,the evolution of crack slippage under friction and the stress intensity factor at the crack tip,which was correlated to the growth of artificial cracks.The results show that with the evolution of the displacement field on rock surface,the tip of the crack blocks the displacement transfer which forms a compressive strain concentration area.The development of crack interface slippage has three stages throughout the loading test,that is the non-slip stage,monotonous increase stage and the fluctuating increase stage.Crack propagation and stress distribution at the tip are closely related to the frictional sliding state of the crack interface.When the crack interface is in the state of static friction,the variation of stress intensity factor at the crackle tip is small.While in sliding state,the stress intensity factor at the crack tip increases in volatility with the local sliding of the crack interface.