Abstract:
To reveal the structural evolution law of roof strata in shallow-buried depth working faces with high-intensity mining, this paper takes the 12-upper 302 working face of Buertai Coal Mine as the engineering background. Combined with physical similarity simulation, multi-base displacement observation, drilling and borehole peeping methods, the roof structural evolution process is systematically investigated. The fracture characteristics of lateral roof strata are clarified, and the load transfer mechanism of intense mine pressure behavior in gob-side entry is discussed. The simulation results show that roof fracture evolution under shallow-buried depth high-intensity mining is divided into three stages: cantilever beam, articulated rock beam and short-arm F-shape. The initial caving interval of the working face roof is 40.5 m, and the periodic caving interval ranges from 15.2 m to 27.8 m with an average value of 18.5 m. The overburden structure of middle and upper thick roof strata transforms from long-arm F-shape to short-arm F-shape. During periodic weighting, the lower thick roof presents a cantilever beam structure, while the middle and upper thick roof form articulated rock beam structures. Multi-base displacement observation indicates that the advanced mining influence scope reaches approximately 57 m. Roof displacement undergoes slow increase, sharp increase and stable increase stages, corresponding respectively to elastic deformation of cantilever beam, sliding instability of articulated structure and compaction of high-position structure in simulation tests. The dynamic fracture evolution process and fracture interval of roof strata are determined accordingly. Field measurement obtains lateral roof fracture structural parameters; the lateral hanging roof length of lower thick roof is 13.05 m, and that of middle thick roof is about 17.12 m. Based on the research findings, engineering countermeasures are proposed. The collaborative roof control strategy consisting of “dynamic mining height adjustment, staged differentiated support and multi-parameter intelligent early warning” can effectively mitigate severe mine pressure behavior under shallow buried depth and high-intensity mining.