Effect of freeze-thaw circles on softening behaviors of triaxial stress-strain curve of costal soft soils

In order to understand the variation of mechanical behaviors of soft soils caused by the freeze-thaw circle (FTC), triaxial compressive tests on soft soils after different FTCs are conducted. Six FTC times are designed ranged from zero to seven, and the confining pressure is designed as constant 400 kPa. The relative softening factor is defined as the parameter to discuss the FTC-dependent structural properties of soft soils. The test data show that (1) the failure stress of soft soils decreases nonlinearly with bigger FTC, and its value after fifth FTC becomes about 42% of its original value without any freeze-thaw experience; (2) the softening behaviors of soft soils become weaker and weaker, almost disappear with the relative softening factor tending to be zero after fifth FTC. Consequently, a mathematical model is proposed in order to describe FTC-dependent stress-strain curve, and the relevant method to determine its parameters is presented according to the test data. Finally, good agreements are found between the test data and the simulated results of the proposed model.