Seepage And Structural Evolution Characteristics Of Undisturbed Soil Corroded By Landfill Leachate

Landfills will generate a large amount of landfill leachate during operation and use,which is a high concentration of organic wastewater that will have a significant impact on the soil structure.Landfill leachate affects the microscopic properties of the soil particle arrangement,pore distribution,mineral composition and content,as well as the macroscopic mechanical properties such as compressibility,expansibility,and shear strength.In this paper,the infiltration test,nuclear magnetic resonance test,SEM test and XRD test were carried out to study the influence of landfill leachate on the undisturbed soil permeability and the microstructure variation caused by the leachate.Expansion and contraction tests,consolidation compression tests and direct shear tests were conducted to explore Mechanical properties of contaminated undisturbed soil changes,according to the test results,we can draw the following conclusions:(1)The results of permeation test and nuclear magnetic resonance test show that the permeability of undisturbed soil increases with the increase of pressure difference,regardless of the undisturbed soil or remolded soil.Under the same concentration of landfill leachate corrosion,The higher the concentration,the smaller the permeability coefficient;the same reverse pressure,the same concentration of landfill leachate corrosive intact soil permeability coefficient is far less than that of remolded soil;by the landfill leachate corrosion,the undisturbed soil,the sharp reduction in the number of macropores soil small,small pores change,the internal structure of the soil was severely damaged.(2)The results of XRD,SEM and Particle size analysis tests show that the composition of clay minerals greatly changes under the leachate corroding,the contents of illite ilerite and montmorillonite decrease significantly,while the contents of kaolin and albite increase significantly;Landfill leachate corrosive undisturbed soil so that the surface roughness of soil particles,loose soil structure,change the contact between soil particles,and gradually undermine the soil structure;landfill leachate pollution The volume fraction of soil samples decreased with the increase of leachate concentration and decreased with the increase of backpressure.The average particle size and median diameter of contaminated soil in landfill leachate increased with the height of soil layer.The specific surface area,The radial distance decreases gradually.(3)No-load expansion test,consolidation compression test and direct shear test show that: the structure of the contaminated soil aggregate in the landfill leachate was severely damaged,the macropores decreased greatly and the expansibility was significantly reduced;landfill leachate contaminated soil significantly increased compressibility and engineering properties drastically reduced;landfill leachate contaminated soil internal friction angle increases,the cohesion decreases,the shear strength of decreased.