Threshold value of numerical index and mining height effect of overburden fracture zone height in Shendong Baode shallow coal seam

Abstract

The height of overburden fissure zone is an important index to study the deformation and failure of overburden, but the existing single index can not reflect the fracture degree of surrounding rock in different space parts of stope. Based on 81505 working face of Baode Mine with typical shallow burial conditions in Shendong, the unification of coal sample damage degree and index RFD (Rock Failure Degree) is completed by laboratory experiments, and a similar model and a numerical model are constructed. Based on the index RFD, the maximum destructive depth in numerical simulation is extracted, and the law of development height of overburden mining fissure zone and its variation with mining height are studied by comparing similar simulation results. The results show that the index RFD can well assess the development characteristics of mining fissure zone under typical shallow burial conditions in Shendong. And the development height of fissure zone continuously with the increase of mining height but the growth rate decreases gradually. The research in this paper provides theoretical support and technical basis for distribution and destruction characteristics of fractured zones, occurrence of rock pressure and safe mining.

Keywords

• fracture zone
• shallow coal seam
• mining caving zone
• mining height
• rock failure degree