Experimental Study on Rockburst of Roadways with Hidden Joints at Different Locations under Disturbance

In order to explore the influence mechanism of joint position on rockburst of straight wall arched roadway under dynamic and static loads, the limestone of Huize Lead-Zinc Mine in Yunnan Province was selected and processed into cube specimens with straight wall arched holes. The joints were prefabricated, and the spacing between the joints and the straight wall was 5 mm, 10 mm, 15 mm, and 20 mm, and the jointless specimens were set as the control. Based on the true triaxial rockburst test system, the rockburst simulation tests of roadways with different joint positions were carried out. Combined with video, acoustic emission monitoring, and fractal theory, the influence of joint position on rockbursts was analyzed from the aspects of rockburst failure process, rockburst pit morphology, acoustic emission signal, and debris characteristics. The results show that: (1) The rockburst failure stage of all specimens were same, and the depth of the rockburst pit decreases with the increase of the distance between the joint and the straight wall. (2) The absolute energy of acoustic emission and the fractal dimension of debris reflect the rockburst intensity. Both of them and the rockburst intensity decrease with the increase of the distance between the joint and the tunnel wall. (3) The farther the joint is from the tunnel wall, the lower the energy consumption of rockburst, and the more obvious the flake characteristics of debris.