The Study On Mechanical Property Test And Its Constitutive Model Of Freeze Saline Soil

The specific characteristics of saline soil itself has a great harm to the soil and the engineering construction, and in high altitude cool region, the calculation and design of the path involves the more complex geological conditions and stress state. Considering the above situation, the original concept of freezing and thawing soil mechanics can not or cannot be completely applicable to engineering practice. In this paper, through the indoor experiment of uniaxial compression and uniaxial creep and triaxial shear test to study the mechanical properties of freezing saline soil and its constitutive model. Considering the influence of many factors, such as loading way, load rate, freezing temperature, soluble salt content, soil properties, and the size of the confining pressure, stress path test, the following several conclusions are obtained.(1)The result of uniaxial compression experiment shows that so many elements has a great influence on the strength of the frozen soil, such as the loading rate, freezing temperature, soluble salt content, moisture content. Increasing loading rate, reducing of the temperature and increasing of moisture content will be to increase the strength of frozen soil in different degree, however, the improvement of salt can reduce the intensity of the frozen soil.(2)The creep constitutive equation of the relationship between stress-strain and time, temperature, soluble salt content by multiple regression and nonlinear fitting is found based on the uniaxial creep experiments.(3)The results of triaxial shear test of different temperature and confining pressured and different salinity is gotten through the test. Results show that the stress-strain curve under different condition is basically a parabolic shape. With the increase of axial strain, when the axial strain isε≤(1.0%-7.5%), deviator principal stress difference is growing fast, and the curve approximates into linear. Saline soil is characterized by a certain elastic properties, which called elastomer phase. As the continuous increase of axial strain, The change of the deviator principal stress becomes smaller, and the curve is obviously nonlinear, which called plastic phase.(4)In this paper, based on the modified calm-clay mode of elastic-plastic model, through the triaxial shear characteristics test of frozen saline soil, the model parameters is determined, and constitutive model of frozen saline soil is proposed.