Influence of Sealing Wall Crack on Gas Migration in Working Face without Coal Pillar Under Gob Connectivity

Aiming at the problem of gas control in the working face of gob-side entry retention, taking the 97,312 fully mechanized mining face of Shaft No. 2 in Sihe Coal Mine as the research object, combined with numerical simulation and field measurement, the influence of the sealing wall crack on the gas migration rule of the goaf under the state of the adjacent goaf connection is studied. The results show that the simulation results match those measured in the field. The established physical model and numerical simulation model of goaf can better simulate the 97,312 goaf gas migration law. Considering the connection between 97,312 goaf and 97,311 goaf and 97,310 goaf, compared with only considering the connection between 97,312 goaf and 97,311 goaf, the maximum gas concentration difference between 97,312 fully mechanized mining face and 97,224 lane gob-side entry retention is only 0.01%, and the gas concentration has no significant change. Therefore, only the connection of 97,312 goaf with 97,311 goaf is considered. It can meet the demand for research on gas migration law in 97,312 goaf. The connection between 97,312 goaf and 97,311 goaf can well reflect the study of gas migration law in 97,312 goaf. The tightness of the gob-side entry retention sealing wall directly affects the gas concentration in the gob-side entry retention. With the sealing wall's porosity increasing, the gas concentration in the corner of the return air gradually decreases. In contrast, the gas concentration in gob-side entry retention gradually increases. In order to prevent the gas concentration in gob-side entry retention from exceeding the limit, the porosity of the sealing wall on the side of the gob-side entry retention should be lower than 10%.