长期静水浸泡对三峡库区滑带土物理-化学-力学性质的影响
摘要
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-strain relationship of the sliding zone soil changes from a strong softening type to a weakly softening type under low normal stress, and from a softening type to a hardening type under high normal stress.The shear strength parameters decrease exponentially with the increase of immersion time, and the decrease of cohesion is greater than internal friction angle.The research results can provide a theoretical basis for the stability evaluation of reservoir landslide.