Effect of long-term immersion in static water on the physical, chemical, and mechanical properties of sliding zone soil in the Three Gorges Reservoir area

The impoundment of the Three Gorges Reservoir has caused a large amount of soil on the bank to be immersed for a long time, which may cause the soil softened and induce instability of landslide.In order to study the effect of long-term immersion on the physical, chemical and mechanical properties of the landslide soil, the immersion softening test is carried out on the undisturbed sliding zone soil of Majiagou landslide.By comparing the particle size distribution, limit moisture content, the characteristics of chemical and mineral composition, shear characteristics, etc., this paper discusses the immersion softening mechanism of sliding zone soil.The results show that ions, such as Ca2+, Mg2+ in the sliding zone soil are largely lost during the immersion process, but the mineral composition does not change.After the immersion, the sliding zone soil appears staged particle size refinement, with which the liquid limit, plastic limit and plasticity index increase.As the immersion time increases, the stress-strai