关键词: 冻融循环, 冰碛土, 力学特性, 损伤统计本构模型

Abstract: To investigate the mechanical properties and damage mechanisms of typical glacial soil in Yunnan, triaxial shear tests were conducted using a TSZ-2 automatic strain control triaxial apparatus under various influencing factors. The mechanical properties of glacial soil were analyzed under varying temperatures, confining pressures, and water contents. A statistical damage constitutive model incorporating a coupling damage variable D (freeze-thaw and load) was employed to characterize the deviatoric stress-strain relationship. The results indicate that under low confining pressures, variations in initial water content significantly affect the deviatoric stress-strain curves and failure strengths. However, the magnitude of these discrepancies diminishes progressively under increasing confining pressures. Under high confining pressures, freeze-thaw cycles have minimal impact on soil with optimal water content w_opt of 19%, which exhibits high cohesion and low failure strength damage. As freezing temperature increases, the deviatoric stress-strain curves soften, and soil strength decreases; however, the overall deviatoric stress strength remains unchanged. Confining pressure reduces the deterioration effect, and the damage caused by the first freeze-thaw cycle is particularly significant. The total damage rate increases with rising freezing temperatures, while soil at optimal water content exhibits the lowest total loss rate. An increase in the number of freeze-thaw cycles reduces deviatoric stress strength, with the first decrease being the most pronounced and influenced by water content. The internal friction angle and cohesion significantly decrease as freeze-thaw cycles progress, whereas soil specimens at optimal moisture content exhibit lower degradation rates. The statistical damage constitutive model, incorporating coupling damage variable D effectively characterizes the deviatoric stress-strain relationship based on triaxial test results. Studies have shown that the effect of freeze-thaw cycles on damage is greater than that of freezing temperature.

Key words: freezing-thawing cycles, glacial soil, mechanical properties, statistical damage constitutive model