Movement of roof strata in extra-thick coal seams in top-coal caving mining based on a high precision micro-seismic monitoring system

By using an underground high-precision micro-seismic monitoring system, the dynamic development law and the distribution pattern of micro-seismic events (MS events) were analyzed, and the movement law of roof strata in extra-thick coal seams in the fully mechanized top-coal caving mining workface was inferred in combination with the mine pressure and strata movement theory and the rock mechanics theory. Monitoring results show that MS events in higher strata and lower strata are of low-density distribution and high-density distribution, respectively. Comparative studies on the horizon and maximum amplitude energy sum of micro-seismic waves indicate that MS events reveal periodical distribution in height and time. Further more, the movement law of roof strata in extra-thick coal seams in the fully mechanized top-coal caving mining workface was inferred. Macro-observations of support pressure show the conclusion of periodic movement of roof strata is reasonable.