Research progress of coarse-grained slip zone soil in China

The study on the strength characteristics of slip zone soils is an important part of landslide stability analysis. Current research on slip zone soils has concentrated on fine-grained slip zone soils. Meanwhile, investigations on slip zone soils that contain coarse particles are scarce. This study focuses on a review and analysis of the influence of specific factors, such as coarse-grained content, moisture content, and mineral composition, as well as the micro and meso aspects and numerical simulations on the strength characteristics of slip zone soils, based on a brief summary of the distribution range and geological characteristics of this type of slip zone soil. The concept of coarse-grained slip zone soils is proposed and compared with soil–rock mixtures. Research showed that the content, shape, size of the coarse particles, moisture content, and the composition and proportion of the clay minerals have an influence on the strength parameters of the slip zone soil. The deformation mechanism of the slip zone soil is further revealed from the perspective of particle deformation and movement at the micro- and meso-level, and the research method of combining macro, meso, and micro is emphasized. Finally, several aspects that should be strengthened in the research work are pointed out, such as the influence of coarse particle difference (content, shape, etc.) on the mechanical properties of the slip zone soil, the development process from meso-deformation to macro-deformation, the internal relationship between macro-parameters and meso-parameters, and the mechanical properties of weak layers of landslides in the permafrost regions.