Modeling of wetting deformation of coarse saline soil with an improved von Wolffersdorff model

Assessment of wetting-induced deformation of coarse saline soil is required to facilitate the settlement control of infrastructures such as the transmission lines in Northwest China. The coarse saline soil exhibits high internal friction angle like common gravels and the cohesion up to 34.6 kPa, as revealed by direct shear tests. Laboratory wetting tests indicate that significant deformation occurs after water immersion, and the higher the water content, the lower the wetting deformation (or the lower the wetting collapsibility coefficient), and the shorter it takes to reach the deformation stability standard (0.01 mm/h). An improved von Wolffersdorff model and water-solute coupled transport model were used to simulate the settlement of coarse saline soil foundation during field immersion test. The effective wetting range (Sr > 60%) rapidly expands in coarse saline soil layer after water immersion, from bulb-shaped wetting front to disc-shaped, like the profiles of pore water pressure. Solute moves synchronously with water, primarily in the mode of convective diffusion. Compared with the limited horizontal deformation, settlement of foundation mainly occurs in the vertical direction, and increases with stepwise load.