Study on landfill gas migration in landfilled municipal solid waste based on gas-solid coupling model

Gas migration rule is of great significance to the safe disposal of landfill. In this article, a gas-solid coupling model was developed and used to simulate the effects of various factors on gas migration. The simulation results showed that gas pressure in landfill decreased with the increase of extraction pressure, anisotropy ratio, coverage gas permeability, extraction well depth, and coverage thickness. The maximum value of gas pressure could reach 683 Pa. Among these factors, extraction pressure played the largest role in the gas pressure, while coverage thickness played the smallest role in it. The radius of influence (RoI) and gas flow rate increased with the increase of extraction pressure, refuse gas permeability, coverage thickness, and the extraction well depth, but with the decrease of coverage gas permeability. The effect of extraction well depth on RoI and gas flow rate was the most significant. When extraction well depth increased from 0.5 landfill height to 0.9 landfill height, the maximum values of RoI and extraction volume increased by 20 m and 20 m(3)/hr, respectively. It was suggested that the design of landfill gas (LFG) collection system should consider the influence of various factors in practical engineering.