Surface Wave Imaging Method Based on Spatial Autocorrelation Principle for Mining Microseismic Monitoring

Microseismic monitoring is a necessary method for ensuring mining safety. Seismic waves such as P-waves can be used to estimate the location of microseismic events caused by rock failures and to obtain additional information on the dynamic evolution process of disasters by analyzing amplitude and frequency changes in microseismic wave signals. However, the surface, which is also characterized by the geophysical characteristic of rock strata, waves recorded by the microseismic sensors are dominant components after microseismic waves transmit over a certain distance. In view of microseismic monitoring of mine safety, this study illustrates a four-line staggered grid survey layout to obtain the velocity structure of mining rocks from microseismic records. A four-line, staggered grid, and circular microseismic monitoring array survey layout records the surface waves traveling from different directions because microseismic events are randomly induced by rock failures or mechanical vibration etc. Surface wave information, which is mainly the Love surface phase velocity traveling between the coal seam and its surrounding rocks, can be extracted from microseismic records using this survey layout and spatial autocorrelation method. The results show that the velocity image characteristics of the mining workplaces are consistent with the thickness distribution of the coal seam. This method is particularly appropriate for mine disaster monitoring because surface waves are not affected by the shielding effect of high-speed geological structure and stratum.