Experiment And Analysis Of Salt Expansion Characteristics Of Saline Soil In The Songnen Plain

Salinized soil in the high latitude seasonal frozen area of Songnen Plain(western Heilongjiang)is a special soil with different salinization and alkalization characteristics.Winter frost heaving,summer thawing,frost heaving and salt heaving in salinized soil lead to road churn,dissolution,slope instability,corrosion of bridges and culverts,and cause many kinds of damage effects,such as power transmission line pedestal pullout and so on,and cause secondary freezing and thawing disasters.In this paper,the characteristics of frost heave response of carbonated soda-type saline soil in Songnen Plain were studied under the conditions of different salt content,water content,dry density,freeze-thaw cycle times and so on.The changes of physical and mechanical properties of carbonated saline soil during freezing and thawing were studied,and the mechanism of the change was revealed.Based on the experimental results,a multivariate linear regression model of shear strength index was established.It provides a theoretical basis for the prevention and control of engineering freezing injury of carbonate soil in seasonal frozen area.The main research contents include:(1)The distribution of salinized soil,the basic engineering characteristics and the main engineering diseases caused by the salinized soil are understood through the field sampling observation and previous research results.(2)Through the basic physical and chemical property test,the material composition,the particle size composition,the water content,the liquid plastic limit,the soluble salt content and the electric conductivity of the soil at different depths were obtained.(3)Through single factor frost heaving test,the frost heave property of soil under different influence factors is analyzed,and the variation law and shear strength of soil frost heave under the influence of salt content,water content,dry density and times offreezing and thawing cycle are obtained.(4)On the basis of the least square principle,the multiple linear regression equation is established and analyzed.The prediction model of salt swelling of the shear strength index in the salt content,water content,dry density and the freezing thawing cycle times is established.The test model is well fitted with the actual situation.