Dynamic law of gas emission of coal seam in roadway drivage based on solid and gas coupling model

To investigate the dynamic law of gas emission of coal seam in roadway drivage,a gas emission flux calcula- tion method combining solid gas coupling FEA model of cross section and time integration method was built. The model was then validated by site observation and the following findings were obtained. The relation of gas emission flux of continuous drivage with constant speed to distance and time obtained by numerical calculation is well fitted by expo- nent decay polynomials. Discontinuous extraction holds zigzag shape but similar overall gas flux trend and the flux difference tends to be constant when driving time is large enough. Coal seam gas pressure has a great influence on gas emission flux and the growing rate of gas emission flux with distance soars with coal seam gas pressure while a critical value exists above which the gas emission flux in the later stage of driving process may have a great possibility for methane concentration exceeding the lower explosion limit.