Abstract:
Geological anomaly areas in coal mines, characterized by high in-situ stress, elevated gas pressure, low permeability, and the development of tectonic coal, represent high-risk areas for coal and gas outbursts. Existing outburst-prevention techniques often suffer from stress superposition, insufficient pressure relief, and low gas drainage efficiency. To address these challenges, this study proposes for the first time the energy unit cutting theory for geological anomaly areas, accompanied by the development of pressure-relief and permeability-enhancement technologies and equipment. The main contributions are as follows: An energy unit cutting theory was established based on outburst potential distribution and energy threshold criteria, dividing coal seams in abnormal areas into high- and low-energy units. By cutting the medium to block chain-type energy transfer pathways, a cooperative permeability-enhancement technology integrating pneumatic (or hydraulic) slotting and controllable directional shaped-charge blasting was developed, achieving intra-unit stress rebalancing and staged gas energy release. Considering the hydrostatic tendency of in-situ coal-measure soft rock, a novel in-situ stress detection method was invented. By coupling drilling energy input, cuttings yield, and particle size distribution, the magnitude of in-situ stress was quantified. Furthermore, a tri-modal real-time sensing device was developed, integrating 2D visible-light cameras, high-resolution 3D time-of-flight cameras, and nine-axis attitude sensors. Fusing multi-source borehole data, a dynamic 3D visualization model of boreholes was established for precise detection of geological anomalies. Based on an explosion-proof screw air compressor, a gas–liquid two-phase collaborative slotting technology was developed, raising pneumatic pressure to 2 MPa. A wind–water conversion structure was invented to integrate high-pressure water jetting with pneumatic pulsing, effectively solving borehole sticking, bit jamming, blockage, and poor cuttings removal in complex soft-hard coal seams. This doubled the gas drainage concentration and significantly prolonged the effective drainage period per borehole. The mechanism of slotting–blasting cooperative permeability enhancement was revealed: slotting provides free surfaces and migration space for blasting, while blast-induced fractures interconnect with circumferential slotting fractures to form a permeable network. Field applications demonstrated that, 30 days after directional shaped-charge blasting, residual gas content in abnormal areas decreased below 3.9 m
3/t, and cuttings desorption indices were well below critical outburst thresholds. Consequently, outburst risk was significantly reduced, and roadway advance rates increased by more than 20 meters per month.