Strength characteristics of slip zone soils of the Tongjiaping landslide in the Three Gorges Reservoir area under different ring shear conditions

Abstract

Studying the strength characteristics of slip zone soils under different shear conditions is of great significance for the stability evaluation of reservoir landslides. Aiming at the weak research on the mechanical properties of landslide zone soil in the reservoir bank accumulation layer at present, in this paper, the Tongjiaping landslide slip zone soil in the Three Gorges Reservoir area is taken as an example to research the strength variation characteristics of slip zone soils under different shear test conditions. The ARS-E2 ring shear apparatus is employed to operate the shear modes of constant velocity, acceleration and deceleration on the strength variation characteristics of the slip zone soil. The experimental results indicate that the stable residual strength of slip soil samples tends to be obtained under constant low-speed shear conditions; meanwhile, the phenomenon of 'strain softening' is prone to appearing after reaching the peak strength. Moreover, the change trend of shear stress is basically the same whether accelerated ring shear or decelerated ring shear under the same shear stress condition, which both have a positive correlation with the normal stress. However, the change in shear rate will significantly affect the peak cohesion of slip zone soils. The research results reveal the mechanical properties of the sliding zone soil under different ring shear conditions, which provide a theoretical basis for revealing the mechanical mechanism of the deformation and failure of reservoir bank accumulation landslides.

Keywords

• slip zone soil
• ring shear test
• shear rate
• peak strength
• residual strength
• tongjiaping landslide
• three gorges reservoir area