Study on Mechanism of Instability Induced Scour of Thick Hard Rock-Coal Pil-lar Structure in Deep Mining Height Fully Mechanized Working Face

The instability-induced rockburst of thick hard rock stratum-coal pillar structure is a typical rockburst mode in Ordos deep mining area, and its mechanism is still unclear. Taking the 30202 working face of a mine in Ordos deep mining area as the engineering background, this paper studies the instability-induced rockburst mechanism of thick hard rock stratum-coal pillar structure in deep fully mechanized mining face with large mining height by means of theoretical analysis, numerical simulation and field measurement, and draws the following conclusions: The spatial movement characteristics of thick hard rock stratum-coal pillar structure in deep fully mechanized mining face with large mining height are discussed. The mechanism of instability induced impact of the thick and hard rock stratum-coal pillar structure is revealed: the foundation stress of the section coal pillar comes from the self-weight of the in-plane thick and hard rock stratum group and the adjacent mined-out area, when the in-plane thick and hard rock stratum reaches the strength limit, it breaks in a "W" shape and transmits additional stress, and when the superimposed stress of the section coal pillar exceeds its failure threshold, local or even whole instability impact occurs. It is found by numerical simulation that the load transmitted by the "W"-shaped twice breaking motion of the thick and hard strata group is the main stress source of the instability impact of the coal pillar near the working face. The control system of instability induced impact of thick hard rock stratum-coal pillar structure in deep fully mechanized mining face with large mining height is designed and implemented, including strong unloading of bearing coal pillar, strong support in disturbed area and strong control of advancing speed. The effect evaluation verifies that the anti-impact system can ensure the safe mining of the working face.