Model Test Study On Pollutant Transport Law Under Large Strain Consolidation

The treatment of municipal solid waste is mainly simple landfill in China.Considering’ engineering cost and technical difficulty,lots of landfill anti-seepage cushion is constructed by compacted natural clay.Thus,preventing landfill leachate from penetrating clay impermeable layer is the key point of the construction of landfill.Research on pollutant migration law is the focus of the design of landfill seepage prevention,which is of significance to extend the service life of landfill and keep environment from damage.Based on the Natural Science Foundation of China:’Study on Multidimensional Coupling Theory of Large Strain Consolidation and Pollutant Transport of Saturated clay’,this dissertation aims to study the migration and diffusion of pollutant within saturated clay regarding to large strain consolidation.In the first place,based on the similarity theorem,according to univariate analysis,orthogonal test design method and sensitivity analysis method,a model soil which conforms to model test conditions is prepared.Besides,the model test was designed independently,and the migration law of both non-absorptive contaminating ions and absorptive contaminating ions under different deformation conditions is studied.Eventually,numerical simulation is carried out for the model test with the help of COMSOL which is a kind of multi-field coupled numerical software.By the comparison of calculated data and model test data,the mutual verification between model test and numerical simulation is generally achieved.Specific research content and conclusions are listed as follows:(1)With kaolinite clay,sand,petrolatum and silicone oil as the basic material,the model soil is successfully prepared to meet the requirements of the model test,and the quality ratio relationship is sand-clay ratio 1:2,aggregate-cement ratio 6:1 and silicone-vaseline ratio.1:1.The physical parameters of this model soil meets the model test requirements and also satisfy the water characteristics requirements.(2)According to the independently designed model test,the effects of soil deformation conditions on the migration of pollutants are studied.Research shows that for nonadsorbed ions,soil consolidation deformation(especially large strain consolidation)will promote the migration of pollutants.Consequently,ability of the landfill’s anti-seepage analyzed by large strain consolidation is much weaker than that analyzed by rigid medium and small strain consolidation analysis.(3)The migrating length of adsorbent contaminants is much less than non-adsorbent contaminants.What’s more,although the migration of adsorbent contaminants is also accelerated by large strain consolidation,compared with non-adsorbent ion,the impact of soil deformation has been relatively reduced.(4)Based on the model test data,the expression equation of the concentration of attenuating pollutants is fitted.This processing method of pollution source concentration is more close to engineering practice.So the distribution of pollutants measured by model test is more realistic and this model test can be more valued(5)Based on COMSOL Multiphysics software platform and model test,a coupling model of clay consolidation and pollutant migration is established,and the numerical results are compared with the concentration of contaminant measured by model test.Despite of some differences,general description of the pollutant migration is similar,and mutual verification between model test and numerical simulation is generally realized.