Research on SWCC of Expansive Soil Considering Cumulative Damage Effect of Dry Wet Cycle

In order to investigate the influence of the cracks generated in the cyclic drying and wetting process on the soil water characteristics of the expansive soil, the soil water characteristics curves of column soil samples subjected to 0 to 3 drying and wetting cycles were tested. Combined with the CT scan results, the cross-section and overall damage variables of the column soil samples were constructed based on the fractal characteristics of cracks. Then the influence of cracks development on soil water characteristics of expansive soils was demonstrated through the changing disciplines of the damage variables. The research results indicated that the surface fractal dimensions of the crack approximately decreased gradually and linearly along the depth. Also, the crack development process showed similar trend in different drying and wetting cycles. The damage variables constructed based on the fractal dimension of the cracks could well describe the cumulative damage effect of drying and wetting cycles on the expansive soil. The overall damage variables of the soil column gradually increased with the number of drying and wetting cycles, and the growth rate gradually increased. The proposed Fredlund-Xing model modified based on the overall damage variables of soil column could well describe the soil water characteristic curve of cracked expansive soil. The research results presented in this study could provide theoretical support for the subsequent research on the seepage and engineering properties of cracked expansive soils.