Experimental Study on Ultra-low Friction Effect of Granite Block Under Coupled Static and Dynamic Loads.

Zonal disintegration widely exists in the excavation roadways and caverns in deep rock masses. Ultra-low friction can be generated in the deep fractured rock masses, which reduces or disappears under dynamic loading. In this paper, granite blocks were processed into cube specimens with a cylindrical hole in center. Static loads and sinusoidal disturbances were applied to study the sliding phenomenon between blocks. During the experiments, real-time images, and acoustic emissions were recorded. Results indicate blocks above the cylindrical hole slide during the second half of the sinusoidal disturbance, and block sliding is caused by a reduction of friction between the blocks. The existence of ultra-low friction can be inferred from this experiment. [ABSTRACT FROM AUTHOR]