Abstract:

The combined action of convection and diffusion leads to the landfill gas (LFG) transport in landfill. Based on the seepage mechanics and solute transport theory of porous media, the governing equation of LFG migration was deduced in the two-dimension scalar coordinate with LFG generation characteristic model. And the computation model of radius of influence for LFG was given. Estimation of radius of influence of gas well and sensitivity analysis of model parameters were presented. The results showed that the gas flux increased with increasing permeability, so as to enlarge the R _i (radius of influence) of LFG. The LFG flow rate was greatly different in the radial direction, caused by the gas diffusion effect, and was the main factor leading to the variation of R _i at different diffusion coefficients. The ratio of flux in outside and hole mouth decreased since the diffusion coefficient of gas in pore increased, leading to smaller R _i. The R _i became larger with decreasing readily biodegradable proportion, but the increasing rate tended to be smaller .Once the landfill height was ≤10 m, the influence on R _i by biodegradable content was not obvious. The determination of LFG R _i will provide the technical data for gas well design and exploitation and evaluation for LFG reuse.