Damage zoning and damage reduction effect analysis of overlying strata in western mining area of China

Yongqiang Zhao^1,2Xiaolong WANG¹Jie FANG^1,2Jianqi Ma^2*Mengyuan Li^2*Xinjie LIU^1,2Jiangping YAN¹

• ¹Guoneng Shendong Coal Group Co Ltd, Yulin, China
• ²state Key Laboratory of Water Resource Protection and Utilization in Coal Mining，National Institute of Clean and Low Carbon Energy, Beijing 102209，China;, Beijing, China

In the process of mining, the overlying strata are affected by disturbance stress to varying damage, and the causes differ across regions. Measuring the damage degree can guide coal mining, and classifying the overlying rock into different zones provides practical guidance. This paper divides overburden damage into regions based on formation causes, severity characteristics, and other factors, with specific calculation methods provided. UDEC numerical simulation software is used to simulate the damage. The system simulates the development patterns of overlying strata damage under varying conditions of mining height (2-8 m), advancing speed (5-15 m/d), and panel width (280-320 m). Optimal mining parameters are determined through area changes in different zones. The research conclusions are as follows: according to the damage states, the overburden can be divided into four parts: I caving fracture zone, II fracture development zone, III sliding failure zone, and IV slight failure zone. Among these, damage in zones II and IV is relatively light. During mining, emphasis should be placed on reducing the area proportion of zones I and III and increasing that of zones II and IV. When the mining height is low, it mainly influences the proportion of zones I and III. As mining height increases, the proportion rises; beyond a certain point, the main affected area becomes zone II. A larger mining height leads to a larger proportion of zone II. With increased propulsion speed, the surface impact range expands, but severely damaged areas are relatively reduced. As mining width grows, the proportion of seriously damaged areas increases. When the speed in working faces 120401 and 22207 is slow, ore pressure appears dense, overburden fracture develops more fully, and the area proportion of zones I and II increases, reflecting dense surface fracture development. When the advancing speed is high, the area proportion of zones III and IV increases, the damage scope decreases, and surface damage should be relatively reduced.