Experimetal Study On Mechanical Properties Of Seasonal Frozen Soil In Jilin Area

In the process of reform and opening up,the development of economic construction in Northeast China is rapid.Highway,railway,water conservancy and hydropower and other infrastructure construction as the top priority.Soil as the foundation of all projects,the stability and safety of its physical and mechanical properties in the special climate conditions in Northeast China are very important to the structure.With seasonal frozen soil freezing in winter and thawing in summer,the structure of soil particles changes with freezing and thawing,In the process of freezing and thawing,soil is affected by cold.There is a great change had taken place in the physical and mechanical properties after freezing and thawing.Therefore,it is necessary to consider the change of the physical and mechanical properties of the soil after freeze-thaw.To the theoretical and Experimental Research on the physical and mechanical properties of frozen soil in Northeast China is relatively weak,this paper improve the modified vacuum preloading preparation of saturated soil,and make oneself low temperature three axis testing machine.Then the silty clay in Jilin area is taken as the research object.According to the different requirements of the mechanical effect of the shallow soil layer and deep soil layer,a series of soil freeze-thaw cycles were studied.The influence of freeze-thaw cycles on the physical and mechanical properties of silty clay in Jilin area is described in this paper.The main contents are as follows:1.The mechanical properties of seasonal frozen soil at home and abroad are described in detail,and analysis the current situation of freeze-thaw test equipment;2.The seasonal frozen soil in Jilin area was dried and sieved,and the conventional physical property indexes were tested;3.Reform saturated soil samples by vacuum preloading method;4.Freezing and thawing three axis test with unconfined pressure freezing working condition for shallow soil layer;Making three axial tests with different confining pressures(100?200?300?400kPa),different freezing temperature(-3?-7?-12?),different freeze-thaw cycles(0~9times),respectively,the mechanical parameters under different initial conditions are obtained.We compared and analyzed the results of each group,the inherent relationship between the pre freezing and thawing test and the test results is discussed.5.Aimed at three axial compression test on applying ambient pressure at the same time freezing and thawing,the samples with different freezing temperature and different freeze-thaw cycles were measured.The experimental results of each group were compared and analyzed.