Model development and analysis of dynamic gas emission from tunneling face zone

The prediction of dynamic gas emission is of important significance for the prevention of gas accidents. Currently, multifield coupling theory has been applied to gas drainage, but the physical model of gas emission calculation is underused. In our research, a thermo-hydro-mechanical coupled gas emission (THMGE) model was constructed and verified with the results of gas emission in three driven headings. Through calculation, the effects of temperature, time, gas pressure, and tunneling speed on gas emission were analyzed. The research results show that gas emission is controlled by the coupling of the gas migration field, coal stress field, and coal gas temperature field. It is calculated that when the starting temperature is 298-318 K, the average gas emission increases by 3.51-6.13% as the temperature increases by 5 K. For exposure times of 10, 50, and 100 h, the gas emission is 0.47, 0.31, and 0.25 times the starting value, respectively. When the gas pressure is 1.5 and 2.0 MPa, the gas emission is 1.62 and 2.24 times the gas pressure of 1.0 MPa. The correlation coefficient between the model and experimental data is 0.912-0.961 and is successfully applied in the project, which provides a theoretical basis for the control of gas accidents.