基于裂纹的岩石摩擦滑移位移演化实验研究

Experimental study on the displacement evolution of rock interface friction slip based on crack

为研究岩石破坏形成断裂面或结构面后的进一步演化特征,选用一种花岗岩制备了双穿透裂纹试件,采用双剪模型开展了摩擦滑移试验研究。用CCD相机记录试验过程中的散斑图像,并利用数字散斑相关方法对岩石摩擦滑移过程中的水平位移场、竖直位移及水平位移的演化特征进行分析。结果表明:①剪应力缓慢增长阶段的位移演化,由围压起主要作用转变为围压和剪切力共同作用,线性增长阶段则以剪切力作用为主;界面咬合程度及水平错动位移的增减变化可作为界面摩擦滑移的前兆;②水平位移场绕流现象的出现和消失,分别是试件局部和整体滑移的前兆;③位移场云图中部等值线的倾斜角度可表征围压与剪应力的关系,也可作为试件局部和整体滑移的前兆。

To study the further evolution characteristics of the fracture plane or structural plane after rock failure,the granite was chosen and prepared as double penetration crack samples,and the friction sliding tests were conducted using twin-shear model.During the tests,the CCD camera was used to record the speckle images,and the digital speckle method was used to analyze the evolution characteristics of horizontal displacement field,vertical displacement and horizontal displacement in the process of friction sliding.The results show that:①The major role in displacement evolution has changed from confining pressure to a combination of confining pressure and shear stress at the stage of slow growth in shear stress.The displacement evolution is dominated by shear stress at the stage of linear growth in shear stress.The increase and decrease of interface occlusal degree and horizontal alternate displacement can be used as precursors of rock interface friction slip.②The appearance and disappearance of the flow around the horizontal displacement field are the precursors of the local and global slip of the specimen,respectively.③The relationship between confining pressure and shear stress is characterized by the central contour inclination in the nephogram of displacement field,so it can also be used as precursors of partial and global slip of the specimen.