Abstract：Landfill gas(LFG) and leaching solution are generated by bio-degradation in bioreactor landfills inducing the settlement of waste. The deformation and movement of waste matrix result from upper landfill loading and bio-degradation behaviour of organic matter. Based on porous medium fluid(water and gas)-solid coupling and micro-degradation theory，the gas-hydraulic-solid coupling model is developed to describe the dynamic behavior of settlement and LFG flow in landfill. And the finite element model is established. The visualization of matrix deformation and gas generation and transport is presented by numerical simulation. The variation of gas pressure and flow rate with time(year) elapsed after the closure of the landfill is given. The results show that the variation law of waste degradation is coincident with the total stress and porosity of landfill waste. The gas pressure is released by extracting within the landfill. The water saturation increases with the settlement，and the variation amplitude of saturation at the landfill bottom is more obvious than that at the top. The gas flow rate by coupling model agrees well with that by single phase model. The reliability of the coupling model is verified. It will provide technological and theoretical support for further studies on settlement treatment and gas resource reuse of municipal solid waste.
