Creep process and the microstructural evolution of sliding -zone soil

Creep behavior of slip zone soil is closely related to its microstructure. The creeping properties and microstructures of sliding soil have been studied a lot before, but few studies have been made on the microstructure changes in the process of soil in the process of creep due to time effect. In this paper, the sliding zone soil of the Erzhuangke north landslide is selected as the research object, and the creep characteristics of the sliding zone soil are examined by direct shear creep test. SEM image scanning and quantitative analyses of soil samples at different stages in the creep process are conducted by environmental scanning electron microscope. The results show that the slip zone soil sample has obvious creep characteristics under 400 kPa positive stress load, and every level of shear stress loading has attenuation creep and steady -state creep stage, when the shear stress value reaches 255 kPa, the specimen is creeped and destroyed by the transition soil in the process of creep due to the time effect. After loading at each stage, the soil -like shear strain rate is gradually reduced and eventually stabilized, and in the attenuation creep ingressated after shear stress load at all levels, the shear strain rate increases with the increase of loading shear stress. In the process of creep, the number of pores in the soil sample decreases gradually, and the soil particles are repositioned and arranged. As a result, the directivity of pores is enhanced, more and more elongated pores tend to be formed, and the contour of pores becomes smoother, but the roundness becomes worse. With the occurrence of creep failure, the structure formed in the creep process is rapidly destroyed, the directivity of soil structure is weakened, and the number of pores increases sharply.