Borehole-roadway seismic-while-mining tomography using correlation time difference

Using shearer as a source, seismic-while-mining(SWM) technology has realized dynamic, accurate and green intelligent detection in fully mechanized mining faces, and can be used to detect static geological anomaly and dynamic mining geological disasters within the work face. Conventional SWM observation system has the defect of blind area. To solve this problem, a new observation system with detectors installed in both roadway and within boreholes are proposed, which effectively improved the imaging range. Based on seismic interferometry principle, using frequency domain correlation algorithm, this paper turns the SWM signal to explosive source signal, and computes the equivalent shot sets. In SWM CT tomography, the absolute travel time is hard to obtain. therefore, a CT tomographic method that directly using correlation time difference was propose, so as to avoid calculating the exact time of seismic and reduce the dependence on the initial speed. The theoretical model and the actual data prove that using borehole-roadway approach, the imaging range has been effectively expanded. The SWM CT tomography based on correlation time difference can image velocity within work face, with static geological anomaly detected effectively. The continuous monitoring and dynamic imaging characteristic of SWM can also be used to dynamically monitor the stress concentration caused by mining in real time, which is more meaningful for working face mornitoring.