Abstract: In view of the problems of broken roof in the end area and severe dynamic manifestation of surrounding rock caused by simultaneous mining of two working faces, this study examines the fracture structure characteristics of thick and hard roof in different layers. It establishes a fracture mechanics model for thick and hard roof, reveals the mechanism of rock burst induced by thick and hard roof breaking in the simultaneous mining working face, and analyzes the evolution characteristics of static and dynamic load stresses in the overlying strata. A collaborative fracturing technique for thick and hard roof working faces and a layered support system with anchor injection reinforcement, known as the “unloading-solidification” collaborative anti impact control technology, are proposed. Research has shown that thick and hard roofs tend to form a seismic source layer for mine impacts, and their fracture energy release has near-far field effects and regional disaster characteristics, leading to different impact dynamics in mines. The energy released by the fracture of thick and hard roof is related to factors including strength, thickness, occurrence layer, overlying rock load, and critical span of the goaf. As the critical span of the goaf increases, the energy released by the fracture of thick and hard roof also increases. The fracture line of the high-level thick and hard roof located on the side near the goaf is a key shock source point for mine induced rockburst. The middle and low thick and hard cantilever beam structure on the goaf side causes the end of the working face to strike 30–40 m and incline 70–80 m, forming a high static load triangular stress concentration area. The superimposed high-level thick and hard roof breaks and is significantly affected by dynamic loads, resulting in crack development on the immediate roof and sub-critical layer 1 roof within 40 m of the end of the working face, increasing the risk of roof collapse accidents. By adopting the collaborative fracturing and anti-impact control technology for upper and lower wells, the high-level shock source layer can be destroyed, the underground middle and low thick and hard cantilever beam can be severed, and the static and dynamic stress response of surrounding rock in the end area can be reduced. Deep and shallow hole grouting solidification and three-stage collaborative anchoring support can form a layered prestressed support shell, improving the strength and integrity of the fractured roof in the end area and enhancing the anti-impact performance of surrounding rock. On-site implementation of the “unloading-solidification” collaborative anti-impact measures results in a 19.2%–20.4% reduction in surrounding rock stress, a 74.0%–77.2% reduction in deformation, a 24.2% reduction in support pressure, decreases dynamic load disturbance on the roof, reduces plastic zone of the surrounding rock, and significantly improves the stability of the surrounding rock in the mining area.

Key words: rock burst, thick and hard roof, simultaneous mining working face, collaborative anti-impact, stress wave