Temporal and spatial characteristics of displacement field of rock friction and sliding

The double-sided shear model experiment was applied to study the friction and sliding of granite specimens. The experimental image gathering system was constructed with CCD camera. Meanwhile，by using the digital speckle correlation method，the evolution characteristics of the displacement field，sliding displacement on the sliding surface and deformation energy density of specimens during friction and sliding were studied. The results of the study show that：in the initial slow growth phase of shear stress，the non-uniform spatial distribution of displacement field in the sliding rock is caused by the random defects in the specimen and the deformation of the concave and convex body randomly distributed on the sliding surface. The displacement is mainly the elastic deformation of specimen. In the linear growth phase of shear stress，a certain part of the specimen is in sliding state. The spatial distribution of the displacement field is dominated by sliding surface，and the whole displacement field of the specimen shows a characteristic of regular distribution. In the nonlinear growth phase of shear stress，the sliding surface has strong and weak sections spatially. The displacement contour lines of the weak section on the sliding surface display uniformly，approximately in straight and parallel. While in the strong section on the sliding surface，the displacement contour lines are non-uniformly distributed curves. The strong and weak sections change with loading process. The factor affecting the distribution of the strong section on the sliding surface is the hindrance of the concave and convex bodies. The hindrance of the concave and convex body is not only related to its own strength，but also related to the degree of occlusion on the sliding surfaces in this area. The horizontal displacement is controlled by the sliding condition of the strong section on the sliding surface. The horizontal displacement curve has a good correspondence with the loading curve. In the nonlinear growth phase of shear stress，static friction and sliding appear alternately on the strong section of sliding surface. The sliding velocity on the sliding surface varies drastically. Meanwhile，the deformation energy density begins to accumulate and release in this phase. © 2018, Science Press. All right reserved.