干湿循环对滑带土基质吸力与抗剪强度的影响.

As the slip zone is the weak zone in the landslide, it is the key part to control the stability of the landslide. The study on the change of unsaturated mechanical properties of the sliding zone soil during the drying-wetting cycle is of great significance to understand the change of shear strength of the sliding zone soil with periodic fluctuation of reservoir water and the resulting landslide deformation and even instability process. The sliding zone soil of a talus landslide in Three Gorges reservoir area was used as the research target. Through the simulation of 0-5 drying-wetting cycles, the direct shear and nuclear magnetic resonance (NMR) tests were carried out on the remolded samples of the sliding zone soil, and the matric suction of the samples after shear was measured by filter paper method. Further, the variation characteristics of pore structure, matric suction, soil water characteristic curve (SWCC) and shear strength of unsaturated sliding zone soil during drying-wetting cycle were analyzed, and the prediction model of unsaturated shear strength under drying-wetting cycle was established based on the test results. The results show that the connection between particles in the soil is constantly damaged and destroyed by the drying-wetting cycle, causing the continuous development and expansion of small pores in the sample to evolve into large pores, and the overall porosity increases because the number of pores in the soil increases; meanwhile, the air intake value and the residual water content of soil gradually decreases with the increase of drying-wetting cycles, which means that the water is easier to penetrate and overflow into the soil pores, and the water holding capacity of soil gradually decreases; besides, the degradation of shear strength of slip zone soil is very obvious under drying-wetting cycle; the cohesion and internal friction angle of slip zone soil decrease gradually with the number of drying-wetting cycles, and the degree of weakening of the cohesion by drying-wetting cycle is greater than that of internal friction angle. Finally, the prediction model of unsaturated shear strength of slip zone soil based on direct shear test and matric suction measurement by filter paper method provides a useful reference for the prediction of shear strength of slip zone soil under drying-wetting cycle. [ABSTRACT FROM AUTHOR]