Sci Rep. 2025 Jul 20;15(1):26342. doi: 10.1038/s41598-025-11849-3.
ABSTRACT
Mastering the deformation and air leakage patterns of gob-side retained roadway in fully mechanized mining faces, as well as the distribution characteristics of the gas flow field, is of great significance for the comprehensive prevention and control of gas in the goaf. Taking the 20,107 fully mechanized mining face of Qincheng Coal Mine in Shanxi Province as a case study, this paper employs fracture mechanics and plate-beam theory to analyze the impact of the roof fracture position on stress concentration and deformation failure of the roadway wall. It is found that when the fracture line is located outside the wall, the supporting stress can be effectively transferred and pressure can be relieved. Based on this, a calculation method for the critical position of roof-cutting and pressure-relief is proposed. Through field measurements and statistical analysis, the quantitative characteristics of the air leakage flow field and gas concentration distribution in the gob-side retained roadway goaf area were obtained. Consequently, a comprehensive gas prevention and control technology for gob-side retained roadway was proposed, which primarily includes directional drilling with staged hydraulic fracturing for roof cutting and pressure relief, along with enhanced coordinated gas extraction. Additionally, it incorporates auxiliary measures such as silicate composite material spraying for leakage sealing, optimization of ventilation pipe parameters in retained roadway, and airflow regulation for pressure reduction. The proposed approach was validated through field practice. The research results indicate that: (1) The air leakage flow field in the 20,107 goaf is characterized by positive-pressure leakage from the intake airflow of the belt roadway and high-concentration gas accumulation on the retained roadway side, which then enters the return airflow. The positive-pressure air leakage volume in the inclined section of the working face (0-36 m) is 332.84 m3/min, accounting for 58.17% of the total, while the air leakage volume in the retained roadway section (36-108 m along the strike) is 408.45 m3/min, accounting for 87.09%. (2) After optimization, the average pure gas extraction rate of directional drilling boreholes (fracturing and extraction boreholes) in the fractured zone reaches 7.46 m3/min, while the average gas concentration in the gob-side retained roadway gradually decreases from 0.59 to 0.34%. These findings provide a theoretical and practical basis for controlling the deformation of gob-side retained roadway walls, reducing air leakage in the goaf, and improving gas extraction efficiency, thereby guiding the safe and efficient production of fully mechanized mining faces.
PMID:40685412 | DOI:10.1038/s41598-025-11849-3
