An experimental study of the creep characteristics of loess landslide sliding zone soil with different water content

Loess slopes are often prone to creeping after being subjected to rainfall, artificial irrigation, river water infiltration, etc. Eventually a landslide occurred, even causing a catastrophic accident. There are few studies on the creep properties of loess landslide soil under different water content in the existing literature, and there is a lack of quantitative analysis of the law. A series of triaxial creep tests of sliding zone soil of loess landslide in the Secaowan Village, Yulin City have been carried. The stress-strain-time curves and isochronous stress-strain curves with different water contents (w=10%，12%，14%，16%，18%, w represents the water content) are obtained and the influence of water content on the creep characteristics of loess is analyzed as well. The long-term strength of loess is obtained by using the isochronous curve method. The research results show that (1) When the water content of the sample is larger, the deviator stress required for the creep failure of the sample is smaller, and the axial strain is larger. This phenomenon can be explained by the electric double layer theory as follows: The thickness of free water increases, the degree of cementation among soil particles decreases, and the water film will lubricate the soil particles and make them easy to slip. (2) When the water content of the sample is larger, the time required for the creep strain to reach a stable state after each level of load is applied is longer. This phenomenon can be explained as follows: The increase of loess moisture reduces the structural integrity of the soil, and the adjustment of the internal structure of the soil is relatively slow under the action of stress. Therefore, it takes a longer time for the pore water pressure to dissipate during consolidation and creep. (3) By analyzing the surface morphology of the creep failure of the loess sample, it is found that when the water content is small, the sample after the creep failure has an obvious shear failure surface. When the water content of the sample is larger, the lateral swelling is more likely to occur, showing the characteristics of plastic failure, and indicating that when the moisture content is larger, the softening effect of water is greater than the effect of water on the crack expansion of the soil. (4) The long-term strength loss rate of loess is introduced. It reveals the law of long-term strength and long-term strength loss rate of loess landslide soil under different water content. The research results can provide a reference for the long-term stability analysis of loess landslides.