Study Of Gas Seepage Numerical Simulation And Disasters Prevention During Tunnel Excavation

:Gas disasters bring great danger in the tunnel construction, cause great loss of lives and property and bad social influence. Tunnel excavation changes the fracture structure of coal, then gas disasters occur with the release of gas. So the study of gas migration law during tunnel excavation process has an important theoretical and engineering guiding role in prevention and control of gas disasters. Based on the coal’s fractured structure features and gas diffusion and flow theory, a gas-solid coupled model was set up in this thesis. Then with software, gas migration in the coal seam during tunnel excavation was simulated and analyzed. Combined with existing research and engineering experience, the prevention and control measures of tunnel gas disasters were suggested. The main research achievements are as follows:(1) Based on the analysis of coal’s stress and gas flow theory, a gas-solid coupled model was set up.(2) With software, the simulation of gas seepage in coal seam during tunnel excavation was completed, and the development laws of gas pressure, gas content and gas flow velocity during tunnel excavation were acquired. The influence of buried depth and initial gas pressure to gas seepage were studied by changing boundary conditions and initial gas pressure. And the influence from length of uncovering coal to gas flow patterns was analyzed.(3) Through analyzing several factors that affect gas disasters and project specific conditions, combined with simulation results, both tunnel construction disposal measures and engineering structure disposal measures of the prevention and control of gas disasters were developed.