Experimental Study On Freezing Characteristics Of Cement Improved Soil

The combination of artificial freezing method and improved grouting method can not only significantly improve the strength of weak strata,but also effectively inhibit the frost heaving and thawing settlement phenomenon produced in freezing.However,due to the lack of construction experience,the final construction effect cannot be guaranteed.If the parameters are not selected properly,the project effect cannot be effectively guaranteed,and even engineering accidents may occur in serious cases.Therefore,this paper conducts the following research on the silty clay of typical soil layers that the subway passes through in Fuzhou:Firstly,relevant geotechnical tests are carried out on the improved silty clay to determine the moisture content,permeability,thermal conductivity and freezing temperature of the silty clay with a certain amount of cement slurry,so as to provide relevant parameters for the subsequent numerical simulation.The uniaxial compressive strength test of improved frozen soil is carried out to study the influence law of the uniaxial compressive strength of frozen soil under different cement slurry content,curing age,soil moisture content and freezing temperature,and to study the failure mechanism of improved frozen soil and the change of stress-strain curve.Then,the frost heave and thaw settlement test of the improved silty clay is started.A series of single factor frost heave and thaw settlement tests are conducted on the five factors that affect the frost heave and thaw settlement characteristics of the improved silty clay,namely,the cement slurry content,the curing age,the water cement ratio,the freezing temperature and the water cement ratio,the frost heave and thaw settlement laws of the improved silty clay under each influence factor were obtained,and the optimal cement content of the improved silty clay was determined to be 20%.Through the monitoring of temperature and displacement in the process of frost heave and thaw settlement,the development law of temperature field and displacement field in the process of frost heave and thaw settlement test is obtained.Finally,the basic equations of temperature field and moisture field are selected,and the water heat coupling model established is solved by the software COMSOL Multiphysics to obtain the change rule of the temperature field,moisture field and displacement in the process of frost heaving and thawing settlement of improved soil,and the numerical calculation results are compared with the frost heaving data measured in the test to verify the model.There are 30 figures,6 tables and 72 references in this paper.