Application of seismic velocity tomography in underground coal mines: A case study of Yima mining area, Henan, China

• Ultrasonic technology was conducted at the laboratory-scale.
• Active and passive seismic velocity tomograms were applied at the field-scale.
• Geological structures, stress regimes, and rock burst risks were illustrated.
• Comparisons have been made between the active and passive seismic tomography.

A better understanding of geological structures, stress regimes, and rock burst risks around longwall mining panels can allow for higher extraction efficiency with reduced safety concerns. In this paper, the stress change of rock mass was first examined by using ultrasonic technique into laboratory-scale rock samples. Subsequently, the active and passive seismic velocity tomograms were simultaneously applied into two study cases with field-scale. Similar characteristics can be found between the active and passive tomography results. More specifically, in the first case, a geological discontinuity was clearly indicated by a linear image in both active and passive seismic tomography results. The results of the second case suggest that seismic tomography can be used to infer stress redistribution, and assess rock burst hazard or locate high-seismicity zones. Ultimately, comparisons have been made between the results of active and passive seismic tomography. Active tomography is found to be better applied in accurately detecting stress distribution and geological structures prior to the extraction of longwall panels, while passive tomography has advantages in continuously monitoring the stress changes and assessing rock burst potential during the mining of longwall panels. This study is expected to increase the safety and efficiency of the underground mining.