Effect of suction stress on the strength of rupture zone and stability of landslide

The variation in moisture content and suction stress within rupture zone soils, caused by fluctuations in rainfall and groundwater levels, is critical to landslide stability. In this study, undisturbed rupture zone soil samples were collected from the drainage tunnel of the Outang landslide in the Three Gorges Reservoir area of China. The suction stress and shear strength of the samples with different moisture contents were investigated using a self-developed temperature and humidity controllable uniaxial tensile strength testing device. The results indicate that, as the moisture content progresses from dry to saturated conditions, the suction stress of samples varies from 0 to 656.8 kPa. By incorporating suction stress into the conventional transfer coefficient method for landslide stability analysis, the model now accommodates variations in the moisture content of the rupture zone. Using this extended transfer coefficient method, the factor of safety (FOS) of Sliding mass II was found to vary from 0.977 to 1.444, demonstrating that suction stress significantly influences landslide stability. Furthermore, a linear relationship was identified between the (FOS) and suction stress within the rupture zone, providing a new perspective for evaluating slope stability and predicting landslide failure in response to rainfall and groundwater fluctuations.