Study On The Characteristic Parameters Of Water Properties Of Frozen Soils Of Different Textures In Cold Region

In this paper,two kinds of frozen soil(sand soil and clay soil)commonly found in the cold region of Harbin are studied,and the topographic,geomorphic and hydrometeorological data of Harbin are summarized.Through the analysis of the influencing factors of the permeability coefficient of frozen soil,the initial moisture content,dry density and fine sand content are determined as the control variables.After the test operation of the collected soil samples,such as air drying,screening,drying,water distribution and freezing,the TST-70 permeator is used to carry out the constant head permeability test of frozen sand under the control of single factor variables.Based on the analysis of the influencing factors of water capacity,water holding capacity and water supply capacity of frozen soil,the variation laws of three hydrological parameters of soil with different lithology under the single factor of initial water content,dry density and number of freeze-thaw cycles were determined after the saturation test and water release test.The test shows that:(1)A low freezing point inert liquid is selected to determine the permeability coefficient of frozen soil in cold regions.In this experiment,sodium chloride solution,calcium chloride solution,methanol solution,ethanol solution,glycol solution and other inorganic and organic solutions of different concentrations were selected.The freezing point test was carried out on the selection test solution,and the freezing point of the solution was selected below minus 20 degrees Celsius,and then the ice melting test was carried out to select the poor ice melting liquid.45% glycol solution was selected for the test of permeability coefficient of frozen soil.(2)Initial water content,dry density and fine sand content will affect the permeability coefficient,and the permeability coefficient of frozen sand decreases with the increase of initial water content.The permeability of frozen sand decreases with the increase of dry density.The permeability coefficient of frozen sand decreases with the increase of fine sand content,and the changes of test control variables are all affected by porosity,which has an impact on permeability coefficient.(3)Under freeze-thaw conditions,the initial water content of sand and clay will decrease with the increase of water content.The water capacity and water supply of sand and clay decreased with the increase of dry density,but the water capacity of the two soils increased with the increase of dry density.The variation trend of freeze-thaw cycles for the capacity,holding capacity and water-supply capacity of sand and clay was basically the same,that is,with the increase of freeze-thaw cycles,the capacity,holding capacity and water-supply capacity decreased in the early stage,increased in the middle stage,and remained stable in the late stage.