To explore the precursory characteristics and influencing factors of rockburst in the bifurcation area of coal seam, the evolution and expansion of fracture and the energy accumulation and dissipation characteristics of coal-rock parting-coal structure (CRCS) during failure and instability process are explored from a micro-scopic perspective, and the influence of coal and rock parting parameters on the instability is studied. The following four points are addressed: (1) Compared with the single coal structure or the coal- rock combined structure, the CRCS can more directly reflect the geological structure characteristics of the coal seam in the bifurcated area; (2) The failure and instability process of CRCS includes two types of instability: slip and fracture. The slip instability is characterized by low strength and high energy release, which is very difficult to predict. (3) Before the failure of CRCS, there are several precursor signal characteristics, such as the shortened development time of the "stable—fracture—stable" cycle, abnormal slip dislocation of the contact surface, and rapid accumulation of rock fracture energy. (4) The inclination angle of the contact surface affects the instability form, the strength of the rock parting affects the instability state, and the thickness of the rock parting affects the impact tendency. The research results have important theoretical significance for preventing rockburst caused by failure and instability in bifurcated area of coal seam.

This study, based on a case from the 1314 working face of Xiaoyun Coal Mine, provides an in-depth analysis of the stress and velocity field characteristics of waterproof coal pillars under different porosities during water inrush events. The research emphasizes the significant impact of water inrush on the stress field distribution of coal pillars. Simulation results, validated by field data, reveal that the highest stress concentration occurs on the side of the coal pillar adjacent to the goaf, with the stress distribution under water inundation conditions exhibiting greater irregularity. The findings not only enhance the understanding of stress variations in coal pillars during water inrush events but also offer valuable insights for coal pillar design and monitoring strategies. This research provides critical theoretical support and technical guidance for the safe design and dynamic monitoring of water inrush disaster prevention in coal mines.

Slip and instability of coal‐rock parting‐coal structure (CRCS) subjected to excavation disturbance can easily induce coal‐rock dynamic phenomena in deep coal mines. In this paper, the failure characteristics and influencing factors of CRCS slip and instability were investigated by theoretical analysis, numerical simulations, and field observations. The following main results are addressed: (1) the slip and instability of CRCS induced by excavation are due to stress release, and the damage of the rock parting is partitioned into three parts: shear failure zone, slipping zone, and splitting failure zone from inside to outside with slip; (2) the slip and instability process of CRCS is accompanied by initiation, expansion, and intersection of shear and tensile cracks. The development of the cracks is dominated by shear behaviour, while the tensile crack is the main factor affecting fracture and instability of CRCS; and (3) slip and instability of CRCS are characterized by stick‐slip first and then stable slip, accompanied with high P‐wave velocity and rockburst danger coefficient based on microseismic tomography.

To address the issue of low detection and identification accuracy of water sources and channels under mine water inrush conditions. The effects of lithology, water saturation, and salinity on the conductivity of five kinds of coal and rock were studied. The results show that the resistivities of coking coal, fine sandstones, and coarse sandstones increase with decreasing water saturation and formation water salinity, but those of mudstone and sandy shale are not affected. Sandy shale exhibits abnormally high resistivity under low- and medium-salinity conditions and low resistivity under high-salinity conditions; the resistivity does not change with increasing water salinity, and mudstone is basically not affected. The electromagnetic response characteristics identified for various coal and rock samples can increase the precision of geophysical detection and identification pertaining to mine water filling sources and channels.

Rockburst accidents are highly likely to take place during the mining of coal seams in bifurcated area. A conventional triaxial testing machine and an acoustic emission (AE) monitoring system are employed to investigate the failure and instability characteristics of coal-rock parting-coal structure (CRCS) and its influencing mechanism. The results show that: (1) The instability process of the composite structure under the conventional triaxial path represents a coupled instability process of contact surface slipping and coal/rock fracture. The penetration of tensile fractures into shear fractures serves as the primary cause of the overall instability of the composite structure. (2) Alterations in the main frequency and maximum amplitude, a sharp decrease in the radiant energy index, and a significant increase in the cumulative apparent volume can be utilized as precursor identification information of the slipping and overall instability of the composite structure. (3) The inclination angle of the contact surface, confining pressure, and loading speed have an impact on the instability of the composite structure. Effectively controlling these factors during production can contribute to reducing the risk of impact disasters. The research results can provide theoretical support for the early warning and prevention of rockburst accidents in the bifurcated area.

The extraction of extremely thick coal seams through slicing mining requires leaving behind several island coal pillars in the top slicing, which could lead to rockburst in the bottom slicing. This article proposed a method of alternate exterior entry (AEE) for rockburst prevention based on the stress distribution of bottom slicing. The influences of coal pillar width ( B ) and stress concentration factor ( K ) on stress distribution were explored using two-dimensional stress imaging. The results indicated that K value had a greater effect on stress distribution comparing with B value. Both stress relaxed and stress rate angles increased linearly with an increase in K value. In order to get the optimized location of AEE in the coal mine stress rate angle was chosen as the stress extension angle, which was further verified by field data from 1210 coal faces. Finally, numerical simulation was used to explore the optimized location of special tail entry under dip island coal pillars for rockburst prevention. It was revealed that plan first was found to be most effective due to its presence in a stress-relaxed area, thus verifying the effectiveness of the AEE method for rockburst prevention.