A Highly Accurate Method of Locating Microseismic Events Associated With Rockburst Development Processes in Tunnels

Abstract

Rockbursts occur frequently and cause serious damage in deep tunnels. Microseismic (MS) source location is of great importance and forms the foundation of the MS monitoring technology used in tunnel rockburst hazard mechanism analysis. A highly accurate method for locating MS events that occur during rockburst development in tunnels is proposed here. An anisotropic velocity model, rockburst event monitor, and a global optimization algorithm (particle swarm optimization) are used in tandem to make the proposed method feasible and the location accuracy better. Simulation results show the MS sources can be located more accurately using the proposed method. The average location error is reduced by 20.16 m. Our method was used to locate MS events associated with rockburst development processes occurring in the deep tunnels of the Jinping II hydropower station in China. The location accuracy of the MS events in the rockburst development process is significantly improved. The case study shows that the located MS events are clustered together more closely in the rockburst area. The average distance of all the MS events to the position of the rockburst is reduced from 23.77 to 13.43 m. The method is highly conducive to in-depth analysis of rockburst development processes and investigation of their mechanisms of formation.