Study On Bio-chemical-hydro-mechanical Coupling Model In Degradable Soil

In degradable soil, particles will loss mass and crush into pieces under certain circumstances. As void ratio and grain fabric changed, soil’s geotechnical characteristics and parameters will be different. Knowledge of degradable soil is relevant to some natural processes and soils, like MSW biodegradation in landfills, erosion of fines from embankment dams and calcareous soils in field. Multi-field coupling in degradable soil will be complex. Degradation will provide a source/sink item to mechanical process and soil’s geotechnical characteristics and parameters will change during degradation. The main research works and conclusions are followed:(1) This paper builds up a governing equation for gas transport. And with other researchers’work, a bio-hydro-mechanical-chemical coupling governing equations of degradable soil is given(2) Based on a fit equation of particle size distribution curve, this paper built up a model to predict instinct permeability, relative gas/liquid permeability, diffusion coefficient, bulk diffusion coefficient, Knudsen diffusion coefficient and relation between stress and strain. This paper also improved soil-water characteristics curve prediction model proposed by other researcher. The comparison between simulation result and experimental result shows that this method has a high accuracy.(3) The multi-field coupling model proposed in this paper is used to simulate MSW’s process of degradation, deformation, seepage and solute transport. This paper compares results of different degradation rate, different soil’s geotechnical characteristics, different initial state of soil and reveals the mutual influence between biochemical process and mechanical process(4) The paper analyzes the multi-component gas transport process in landfill cover. The gas component distribution in cover is related with effective bulk diffusion coefficient and gas component at top boundary. The paper analyzes the liquid solute transport process in liner. The result shows liquid solute transport in liner is affected by overlaying load, water pressure and drainage path.