Research on Surrounding Rock Stability Test of Tunneling Roadway under Complex Geological Conditions

Abstract

Different geological conditions are often encountered in the excavation of coal mine roadways, with fault-fracture zone being the most commonly seen complex geological conditions. Fault-fracture zone is characterized by complex lithologic property and joint development and can easily cause safety accidents when excavation burrows through the fault. Therefore, grouting reinforcement of fault-fracture zone is often implemented to ensure coal mine safety production. Based on the tunnel excavation case of −530 - −650 m belt conveyor inclined roadway at Huainan Pan’er Coal Mine, borehole optical fiber and electrical testing technologies were applied to monitor and analyze the dynamics of the surrounding rock stability when roadway excavation passed through the F1 fault, and evaluate the effect of grouting reinforcement on fault-fracture zone. According to the results of optical fiber and electrical methods, the distributional characteristics and evolution patterns of strain and electric resistivity were analyzed. The research pointed out the distinct difference in variation characteristics of strain and electrical fields between grouted reinforced fault-fracture zone and normal rock strata sections. This indicates that the grouting reinforcement effectively improve physical properties of rock strata in the fractured section, the stability of the rock strata at the fault-fracture zone was effectively increased, the degree of fault activation and deformation was relatively small, and roadway surrounding rock basically retained its original properties, pointing to high stability.