ABSTRACT
Based on the discrete element method, this paper presents a new simulation method of freeze-thaw damage, and conducts PFC simulation of loess under different freeze-thaw cycles. Using this method, the simulation results of the unconfined compressive strength of loess under different cycles are similar to the experimental results, which proves the feasibility of this method. Then, the root model is established to simulate the UU triaxial test of the root-soil complex, and the parameters of the numerical model of the root-soil complex are calibrated, to further explore the effect of root angle on the shear strength of the root-soil composite and carry out numerical simulation research on the strength characteristics of the root-soil composite under different freeze-thaw cycles. The results show that: (1) The proposed freezing-thawing damage simulation method can better simulate the deterioration effect of loess under the freezing-thawing cycle. (2) The existence of a root system can improve the shear strength of the soil. Under the same number of freeze-thaw cycles, the shear strength of the root-soil composite is higher than that of plain soil, and the shear strength of the root-soil composite decreases first and then tends to be flat with the increase of freeze-thaw cycles. (3) When the root inclination angle is 30 degrees, it has the greatest effect on improving the strength of the soil. The inclination angle of the root system is 60 degrees, which has the smallest improvement on the strength of the soil. However, when the root inclination angle is 60 degrees, the shear strength of the root-soil composite is least affected by the freezing-thawing cycle. The research results provide a new way to explore the freeze-thaw damage mechanism of root-soil complex from the microscopic point of view, and can also provide guidance for ecological slope engineering construction in cold regions.
