Research on the Characteristics and Control Technology of Gas Disasters in the Gob of the Nonpillar Working Face Based on the DEM-CFD Coupled Model

Gob-side entry retained by cutting roof (GERCR) is a novel and widely used nonpillar mining technology, but the gas emissions from gob are large, and the gas migration characteristics change obviously, which easily leads to serious safety accidents such as gas explosions and personnel suffocation. The discrete element method-computational fluid dynamics (DEM-CFD) coupled model was proposed and used to study the gas flow field in gob under this technology. Through the calculation of this coupled model, the gas distribution and emission characteristics of gob under different ventilation modes of GERCR technology were clarified, and the areas where the gas exceeds the limit in the roadway were determined. To prevent and control gas accumulation, three-dimensional gas drainage technology in the GERCR working face was proposed based on the above research conclusions. Through the field application and monitoring, the characteristics of gas emission and the effect of gas drainage in the gob of GERCR technology were verified. The on-site monitoring results show that the DEM-CFD coupled model established above can simulate well the gas emission characteristics of the GERCR gob, and the three-dimensional drainage system can well control the gas accumulation in the roadway. The research results are of great significance to control gas disasters of this novel nonpillar mining technology.