Abstract: To investigate the effects of freeze-thaw cycles on the mechanical properties of Expansive Soil-Rubber Fiber (ESR),freeze-thaw cycle tests and consolidated undrained triaxial tests were conducted on saturated ESR.The variations in elastic modulus and damage of ESR were analyzed under different freeze-thaw cycles and confining pressure.The results indicate that:(1)Under the influence of freeze-thaw cycles,the elastic modulus of ESR decreases,while rubber fibers can mitigate the degradation of the elastic modulus caused by freeze-thaw cycles;(2)As strain increases,micro-defects in ESR develop into cracks that form rupture surfaces,ultimately leading to failure,with the damage variable approaching 1;(3)The initial damage variable in ESR is positively correlated with the number of freeze-thaw cycles.As rubber fibers serve as tensile elements,the damage evolution curves of ESR intersect successively,illustrating significant plastic characteristics in the later stages of shear;(4)Confining pressure can limit the development of micro-cracks in ESR,and the damage variable of ESR decreases with increasing confining pressure.The results validate the beneficial effects of rubber fibers in enhancing the freeze-thaw resistance of expansive soil,indicating a promising application prospect for backfill materials in frozen soil areas.