Effect of delay time of working face pressure change on airflow direction in gob: A simulation study

For shallow buried mines, the cracks generated due to the mining activities will connect the surface ground and the working face through the gob, which may result in the gas exchange between the surface and underground. In this study, we proposed the gob gas flow model and verified its applicability based on the measured data on site in our previous research and discussed the effect of delay time of pressure variation between working face and surface ground on the airflow direction according to the simulation. The results suggest that the delay time of pressure variation is the main factor affecting the pressure difference between surface and working face and airflow direction. Due to the characteristics of the surface pressure changes, the effect of delay time on airflow in gob is small in a short time, but this effect gradually increases with time. According to the airflow law in a cycle of pressure variation, the airflow direction in the gob is predictable when the delay time reaches a certain value, which can be interpreted clearly on the surface pressure variation diagram. This research may provide references for the measures taken against mine disasters caused by different airflow directions. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.