Study on the Characteristics of Microseismic Source Parameters in Deep Tunnel

In order to analyze the size, mechanism and process of surrounding rock fracture during the excavation of deep tunnel, and improve the safety during the excavation of tunnel. This paper takes the tunnel in Yunnan province as the research object, builds a microseismic monitoring system in the tunnel, uses the double-difference positioning method to locate the microseismic components during the tunnel opening process, and studies the evolution law of source parameters such as energy ratio, static stress drop, dynamic stress drop, etc. The results show that: (1)The failure mode of the surrounding rock during the excavation of the tunnel is mainly tensile failure. (2)The static stress drop of the tunnel is several orders of magnitude smaller than that of natural earthquake and mine microseism, which indicates that the stress adjustment of surrounding rock of the tunnel is relatively small, and the dynamic stress drop of the tunnel is smaller than the static stress drop, which indicates that the surrounding rock of the tunnel is too fractured. (3)The size of source rupture of the tunnel is larger than that of shallow-buried tunnel, but smaller than mine micro-earthquake and natural earthquake. The above results can provide a reference for further study of the fracture process of surrounding rock at the microseismic source during the excavation of deep tunnel, and thus evaluate the risk of tunnel excavation.