Properties And Stability Evaluation Of Life Source Polluted Foundation Soil

The structure and mineral composition of soil changed with migration of life source pollutsants in the soil,and the physical and mechanical properties of the soil can be changed,which lead to the decrease of soil stability and has a serious adverese effect on the engineering construction.The effect of different life source pollutants on the soil properties and mechanism are not same.Therefore,it has both important theoretical and practical significance to study the effect of changes in composition and concentration of life source pollutants on the physical and mechanical properties of soil,to reveal the evolution law of properties for life source polluted soil and to to establish the stability evaluation model of the life source polluted foundation soil.The Cl^-,Ca²⁺,Na⁺,CO₃^2-,CH3COO^- and NH₄⁺that higher content in life source pollutants are selected as pollution source ions.The life source polluted soil was taken as the research object.The change of plasticity,compressibility and shear strength with pollutants composition and concentration for life source polluted soil were studied,the law and mechanism of properties of life source polluted soil were revealed.The changes of microstructure and chemical composition of life source polluted soil with the composition and concentration of pollutants are analyzed by the means of SEM and XRF fluorescence spectrum analysis.The stability evaluation model of the foundation soil take something into consideration which including the properties of soil and influence of pollutants was established by fuzzy evaluation method.The researches indicate as follows:?1?The liquid limit,plastic limit,plasticity index,compression coefficient of the clay polluted by NaCl,Na₂CO₃ and CH₃COOH are positively related to the pollutant concentration;the shear strength of the clay polluted by NaCl,Na₂CO₃ and CH₃COOH is negatively related to the pollutant concentration.The liquid limit,plasticity index,compression coefficient of the clay polluted by CaCO₃ and NH₄Cl are negatively related to the pollutant concentration;the shear strength and plastic limit of the clay polluted by CaCO₃ and NH₄Cl are positively related to the pollutant concentration.?2?The mathematical relationship between the void ratio e,compression index Cc,pressure p and life source pollution concentration s of life source polluted soil is calculated:e?28?e₀?10??Cc₀?10?Bs?lg p₁ p₀?3?The main reason for the change of plasticity,compressibility and shear strength of the typical life source polluted soil is that the exchange adsorption of contaminated ions leads to the change of the thickness of the double layer on the surface of the soil particles,the free oxidation of corrosive acid and the erosion of the colloid,and the change of the mineral composition of the polluted soil.?4?The microstructural parameters such as total pore area,total pore length,porosity and void ratio of CH₃COOH polluted soil compared with unpolluted soil are significantly increased,the microstructural parameters of CaCO₃ polluted soil are smally decreased,The effect of CH₃COOH on clay structure is more significant than CaCO₃.?5?The evolution law of properties for life source polluted soil is revealed.In the early stage of domestic waste degradation,the change of physical and mechanical properties of life source polluted soil by the influence of CH₃COOH;In the late degradation of domestic waste,which played a major role is CO₃^2-and CH₃COOH was not produced.?6?Based on fuzzy evaluation method,the stability evaluation model of life source polluted foundation soil was established.