Study on characteristic of overburden movement in unsymmetrical isolated longwall mining using microseismic technique

摘要

Based on the key stratum theory, overlying strata structures above a typical unsymmetrical isolated working face (LW10302) was analyzed, and a microseismic monitoring was also applied to characterize the fracturing propagations associated with overburden movement in mining progress. The results show that the overlying strata above LW 10302 can be divided into key strata of different grades, and the formed "O-X" fracturing structure have the main and inferior "O-X" ones. The spatial evolution of seismic events demonstrated that seismic activities fits very well with the overburden fracturing patterns and stress manifestation around the longwall face. In the mining process, most of the events located within the surrounding strata of. LW 10301 and 10302 while low energy events distributed mainly in multiple roof and floor strata, and the strong tremors occurred almost within the super-thick primary key strata and appeared to be related to shear fracturing of large-scale overburden movement. Additionally, seismic signals corresponding to different failure mechanisms show different characteristics in waveform features. The study in this paper indicates that microseismic monitoring can provide invaluable information to characterize the mining-induced seismicity and reveal the failure patterns within strata associated with mining, which will greatly benefit the alleviation and prevention of rock burst hazards in mines.