With the increase of mining depth, rock burst disasters frequently occur in steeply inclined coal seams. Firstly, this paper analyzes the rock burst of 5521-20 working face in Yaojie No. 3 coal mine and summarizes the characteristics of rock burst in horizontal section mining of steeply inclined extra-thick coal seam (SIETCS). Then, the static load distribution characteristics and the influence of dynamic load in the horizontal section mining of SIETCS are systematically studied by combining theoretical analysis with numerical simulation. On this basis, the mechanism of rock burst in horizontal section mining of SIETCS is put forward, verified by actual measurement. The results show that the SIETCS is “clamped” under the combined action of the same change trend of roof and floor. The maximum principal stress peak values on the roof and floor sides reach 22.0 MPa and 20.5 MPa. The maximum shear stress earned 8.7 MPa and 8.4 MPa, which makes the shear stress concentration in the coal body high and tends to “shear dislocation.” Under this “shear-clamping” action, an approximate “trapezoidal” plastic zone and a “rectangular” stress concentration zone are formed under the section. With the increase of mining depth, the “shear-clamping” action of SIETCS becomes more and more intense. When the roof cantilever reaches the ultimate span and breaks, the intense dynamic load increases the shear stress and failure of coal, which is easy to induce rock burst. The superimposed load greatly affects the area from the roof side to the middle of the working face, and the rock burst is intense. The rock burst is weak on the floor side due to the pressure relief of the surrounding plastic zone. The monitoring results show that the supports pressure and MS events activity on the roof side and near the middle part of the working face is considerable, while the floor side is opposite, which verifies the research results.

Coal burst is a severe and dynamic hazard, and understanding its mechanism is crucial in preventing such incidents. Strong tremors during the working face mining in the stress anomaly zone of the pinch-out coal seam are frequent. Theoretical analysis, numerical simulation, and field measurement methods are used to analyze the energy evolution law for mining at the working face and mechanism of coal burst. Mechanical models of the inclined and strike overhang structures are established, and the theoretical analysis of the strike and inclined energy distribution characteristics of the working face roof is carried out. The two key areas with a high overhang bending deformation energy accumulation are identified at the lower end and middle-upper part of the working face. The simulation results show that the energy accumulation area of the roof in the inclined coal seam has prominent asymmetric distribution characteristics. The roof energy accumulates in the lower end and middle-upper area of the working face. The floor energy accumulates in the lower end area of the working face, and the peak position of the overhead energy of the working face in the direction shifts toward the coal-wall side. Influenced by the local absence of the No. 8 coal seam, the vertical stress of the surrounding rock at the working face of the massive, inclined coal seam increased by 12.7%; the peak of roof energy at the working face inclination and strike increased by 46.2% and 32.2%; and the range of roof energy accumulation expanded. A deep directional hole blasting plan to prevent the phenomenon at the working face roof is developed, which effectively reduces the stress and energy level of the inclined hanging roof and avoids the occurrence of coal bursts in the abnormal stress area of the working face.

Coal pillar bursts continue to be a severe dynamic hazard. Understanding its mechanism is of paramount importance and crucial in preventing and controlling its occurrence. The extreme roadway deformations from the asymmetric isolated coal pillars in the central mining district of YaoQiao Coal Mine have responded with frequent intense tremors, with risky isolated coal pillar bursts. The theoretical analysis, numerical simulation, and field measurements were done to research the impact of spatial overburden structure and stress distribution characteristics on the isolated coal pillar area, aiming to reveal the mechanism of coal pillar burst leading to the practice of prevention and control in the asymmetric isolated coal pillar area. The study shows that the overburden structure of the asymmetric is an asymmetric “T” structure in the strike-profile, and the stress in the coal pillar is mostly asymmetric “saddle-shaped” distribution, with the peak stress in the east side of the coal pillar, and the coal pillar is a “high stress serrated isolated coal pillar.” Numerical simulation results showed that the support pressure in the isolated coal pillar area on the strike profile was asymmetrically “saddle-shaped” distribution. The peak vertical stress in the coal pillar area continued to rise and gradually shifted to the mining district's deep part. As a result, the response of the roadway sides to the dynamic load disturbance was more pronounced. They developed a coal burst prevention and control program of deep-hole blasting in the roof of asymmetrical isolated coal pillar roof and unloading pressure from coal seam borehole. Monitored data confirmed that the stress concentration was influential in the roadway’s surrounding rock in the asymmetric isolated coal pillar area, circumventing coal pillar burst accidents. The research outcomes reference the prevention and control of coal bursts at isolated working faces of coal pillars under similar conditions.

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Solutions for the maintenance of safety in an isolated working face has not been well achieved; this is attributed to its unique overburden structure and the strong mining-induced stress during the advancement. This paper is devoted to filling this research gap and is based on the case study of LW 10304 in the Xinglongzhuang Coal Mine, in China. The overburden structure and stress distribution characteristics of this isolated working face were theoretically investigated, followed by the development of a comprehensive identification method. The research results showed the following: (1) The overburden strata of LW 10304 is in the form of a short “T” shape and the stress increment is featured with the overall “saddle” shape before the extraction of the isolated working face. During this period, the lower key strata and main key strata affect the stress level at the two ends and the central part of the working face, respectively; (2) Both the frequency and energy of micro-earthquakes in the working face account for more than 95%, which is positively correlated with roof damage and rib spalling, associated with some overlaps between the damaged zones; (3) The fracture movement of inferior key strata near the coal seam plays a dominant role in affecting microseism activity and mining-induced stress. The microseism energy attributed to roof breakage accounts for 43.34% of the overall energy; (4) A comprehensive indexing system, covering microseism frequency, microseism energy, and support resistance, was established to identify the mining-induced stress intensity of the isolated working face. The early warning efficiency of the “strong” degree of mining-induced stress is 0.94, which is believed to provide an option for other isolated working faces with similar geological and mining conditions.