Study on Deformation Characteristics of Coal Roof Overlapping Mining under the Coverage of Magmatic Rocks with DEM Simulation

摘要

It is more complex in roof rock damage of many coal seams by overlapping mining under the coverage of magmatic rocks than that of the single coal seam. The paper simulates the deformation-failure of roof on caving of overlapping face using DEM method to obtain deformation-failure development law. The correlation of cover rock construction feature and directional distribution of bed-separated fissures in caving is researched, and the distribution features of stress on overburden rock and deformation-failure development law of many coal seams by overlapping mining under the coverage of hard rocks are summarized. Stress concentration occurs obviously in upper part of Magmatic rocks above coal7 after coal7 mining, during the course of coal8 mining. Overlapping mining leads to increasing the height of coal seam roof destruction obviously. The results are the reasons why the possibility of conducting the upper aquifers and the water-inrush accident are increased. This research result is supposed to improve the level of water hazard prevention under aquifers. At the same time, the theory of deformation and failure of overlying rock has been enriched in coal seam mining.