Performance and feasibility analysis of two microseismic location methods used in tunnel engineering

The location of microseismic (MS) sources is of fundamental importance in MS monitoring and risk warning. Location accuracy, efficiency and stability are affected by location methods heavily. In this paper, feasibility of two location methods (TDP&S and TDP-S methods) recently used in MS monitoring in tunnel is studied. An efficient global-optimization algorithm, particle swarm optimization (PSO), is introduced to analyze the performance (efficiency, accuracy and stability) of the two methods successfully in a tunnel engineering condition. Results obtained via numerical experimentation show that in a tunnel engineering condition the locations of MS sources with PSO algorithm could be accurately obtained using both the two location method. The relative location errors are mostly in 5.0%. The solution efficiency is greatly improved when using TDP-S location method (the average solution speed increase is 73.9%). And it is less sensitive to the MS source position. However, the TDP&S method is better when there are errors in arrival-times. We should dynamically choose the better location method according to the actual situation. The two methods should be used together to meet the engineering demand sometimes. The two location methods with PSO algorithm were used to find rockburst events in the deeply-buried tunnels of the Jinping II hydropower station in China. The results in this real engineering application agreed with the numerical experimentation results. These results will lay a foundation of the development of MS technique in tunnel engineering.