Study On Subgrade Settlement Characteristics Under The Effect Of Freeze Thaw Cycle

The road is affected by the freezing-thawing cycle and results in large settlement because of the cyclical change of climate in the seasonally frozen region.Cold end temperature,soil water content and freezing-thawing cycle times are important influencing factors in the freezing-thawing cycle,however,in the existing calculation methods of settlement theory,there are few calculation methods which can reflect the influence of cold end temperature,soil moisture and freezing-thawing cycle times on road subsidence.A settlement calculation method is proposed to perfected the influence of temperature,water content and the number of freezing and thawing cycles on the settlement of the road in order to calculate the existing settlement theory.The temperature field and settlement of the experimental section is monitored,and the variation regularity of temperature field and settlement of Subgrade is analyzed based on the project of the Heihe Dalian highway in Baiquan Ming River and Qinggang(Du Jiadian)section.And according to the field measured data,the sample is frozen and thawing in the room,and then the consolidation experiment of the soil after freezing thawing is carried out.The influence of the cold end temperature,the initial water content of the soil and the number of freezing and thawing cycles on the compression modulus Es1-2 and the compression coefficient of the coefficient of Alpha1-2 is studied by the single factor variable method.On this basis,a calculation method which can reflect the influence of cold end temperature,soil moisture content and freezing thawing cycle times on soil settlement is presented by using the stratified summation method and stress strain hyperbolic model,and the settlement calculation of the test section is carried out,and the results of the test section monitoring are compared and analyzed.The results show that the distribution of the temperature field in the Subgrade is changed by the sine function in the year period,and the temperature changes of the subgrade are lagging in different depths,and the freezing thawing effect affects the settlement of the subgrade.Under normal temperature,the compressive modulus Es1-2 of soil and the compression coefficient a1-2 of soil generally have a linear relationship with the initial water content of soil.;at the lowest cold end temperature is-4?,thaw times 3 the scope of the second,the soil initial water content is certain,the compressive modulus Es1-2 of soil mass and the compressibility coefficient a1-2 of soil mass and the times of freezing thawing and thawing are the same.The has a linear relationship with freezing-thawing times and cold-end temperature,and the stress-strain of frozen-thawing soil is full of hyperbolic equation.According to the relationship between the parameters A and B of the hyperbolic model,the relationship between the initial water content,the number of freezing thawing times and the cold end temperature,the e-p curve is derived,and the settlement of the road can be calculated by the combined stratified summation method.The results are compared with the measured data in the field.It is found that the error is within the scope of the work and can be calculated in the future.The road settlement in the frozen area provides a theoretical reference.