In seasonally frozen soil region

the physico-mechanical properties of subgrade soils with different states (plasticity index

confining pressure

etc.) will change after freeze-thaw cycle during the traffic operation; but the study of effects of freeze-thaw cycle is not extensive and intensive and can not provide accurate data to support the roadbed design in roadbed design of seasonally frozen soil region. So this change has not been taken into account. Three subgrade soils with different plasticity indices are selected from seasonal frozen soil region. Static triaxial test is executed on the samples exposed to 0-7 times closed-system freeze-thaw cycles under different confining pressures. Elastic modulus is obtained from the line segment of deviator stress-strain curve. The results show that the elastic modulus increases with confining pressure increase for the same kind of soil under the same freeze-thaw cycles. Elastic modulus with the same confining pressure decreases with the of freeze-thaw cycles; Under the same confining pressure and the same freeze-thaw cycles

elastic modulus increases with the plasticity index. The exponential function is adopted for multiple nonlinear fitting. The relationship between elastic modulus and confining pressure

plasticity index

freeze-thaw cycles is obtained and shows a good correlation.?