Abstract
Coal bursts occurring in steeply inclined coal seams (SICSs) are increasingly severe. To solve this problem, a mechanical model for the distribution of static stress on coal‐rock masses along panels and the distribution of dynamic load induced by the breakage of thick and hard roofs with propagation distance was established. The stress characteristics after a superposition of dynamic and static loads on the roof and floor roadways (Rr and Rf) were determined. In addition, precursory information characteristics and index sensitivities of four indices for dynamic loads and the CT index for static loads based on seismic tomography were separately analyzed. The monitoring and warning indices for SICSs and flat seams were compared. The results showed that the static stress of Rr was significantly higher than that of Rf, which provided a basis for the stress‐triggering coal burst behaviors. Three indices for dynamic loads and seismic tomography results exhibited remarkable precursory information and high sensitivity. However, the performance of lack of shock index is poor. The continuous anomaly and the contradiction of indices at Rr and Rf can be considered as precursory information for predicting coal bursts.
Highlights
Coal bursts occurring in steeply inclined coal seams (SICSs) are increasingly severe
Precursory information characteristics and index sensitivities of four indices for dynamic loads and the CT index for static loads based on seismic tomography were separately analyzed. e monitoring and warning indices for SICSs and flat seams were compared. e results showed that the static stress of Rr was significantly higher than that of Rf, which provided a basis for the stress-triggering coal burst behaviors. ree indices for dynamic loads and seismic tomography results exhibited remarkable precursory information and high sensitivity
Lan [9] suggested that the impact force during section mining of two suberect extra-thick coal seams was generated from the crowbar effect of the rock pillars at the two sides of a gob on the coal mass
Summary
Distribution Characteristics of Static Stress of Coal Rock in a Coal Mine Panel. Under the influence of occurrence structure, stresses on the roof and the floor sides of a coal mine panel in the same horizontal slices are quite different in the SICS. It is mainly affected by self-weight, abutment pressures σr and σf on the roof and floor sides, pressure Pr of overlying rock mass scattered in gob, and abutment pressure Pf of coal mass on the bottom. E stress of bottom coal was determined by stresses on the roof, the floor, and the scattered overlying rock blocks. It was considered that the AE boundary is subjected to uniformly distributed stress σx, while OE side bears the abutment pressure Pf1 of the bottom coal, and the OA side bears nonuniformly distributed abutment pressure σr of the roof. Fr1 and G1 represent the frictional force between the roof and the y
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