Failure characteristics of thick hard roof stratum under hydraulic pre-splitting and its application in a coal mine, Dongsheng mining area

Abstract

Due to the presence of the hard suspended roof, it cannot collapse naturally after being mined in a large-scale goaf. If the roof suddenly destroys without human intervention, it would cause serious disasters. In this paper, we discuss the mechanisms and applications of hydraulic fracturing in alleviating the potential for catastrophic disasters. After the fracturing crack propagation principle, we investigate the failure and stress characteristics of overburden with and without fracturing, taking a mine in Dongsheng mining area. The results show that the regulated roof suffers severe damage after fracturing, and the initial rupture distance of hard roof is reduced to 40 m or so. Additionally, the development height of water-conducting fissure zone is approximately 138.18 m. The fracturing effect can be preliminarily speculated according to fluid pressure curves. It is inferred that hydraulic fracturing point 3 has the best damage effect on the hard suspended roof. On the other hand, a common trait of overburden stress is easily observed by monitoring points, namely that the overburden stress after fracturing shows a relatively smaller value. The study provides theoretical support for the safety management of thick hard roofs, especially in the coal mines seriously affected by roof accidents.