Porosity Prediction with Settlement and Biodegradation in Municipal Landfill

The landfill settlement induced by biodegradation and mechanics compression contribute to changes in rearrangement of waste porosity. Based on the fluid-solid interaction mechanics theory, a new coupling model has been developed to describe the interacting of porosity- displacement-gas pressure with combine to the waste deformation and micro-biological degradation. And the numerical scheme of the model is given. The settlement strain, porosity , permeability and diffusivity is presented by numerical simulation. The simulation results show that the porosity values increase is due to the waste itself decomposition. The waste settlement is the key to the decrease process of porosity. The variant effect of organism content on porosity is different. The maximal amplify of permeability and diffusivity by organic decomposition is 40 % and 23 % in the dispose duration. Predicting the transport process in landfill, the effect of the porosity can not be neglected by comparison the changes of intrinsic permeability and D_e/D_g.