Experimental study on ultra-low friction effect of granite block based on two-dimensional digital image correlation technique

Based on the experimental research of ultra-low friction effect at home and abroad,the experiment of ultra-low friction effect on block rock mass was designed. In this paper,granite block was cut into cube specimens with a cylinder hole in its center. The variation characteristics of the granite block under the dynamic loading combined with the static loading were studied by using the self-developed experimental equipment. The two-dimensional digital image correlation test method (2D-DIC) was used to measure the full-field displacement information of specimen surface, and the acceleration value was obtained based on the displacement information. The curve of friction versus time for block rock mass was obtained based on the Newton’s second law. The main findings show that the 2D-DIC test tech-nology can accurately measure the displacement change of the block rock mass. Based on the displacement,the gaps at two sides of the rock above the hole were gradually increased and the friction was reduced with the effect of horizontal disturbance load. The change of the friction and the disturbance load cycle has the same cycle. It effectively verifies the existence of ultra-low friction phenomenon by using the 2D-DIC technique.