Abstract:Aiming at the problems instability of collapsed hill soil deveoped by granite, the tensile strength characteristics of collapsed hill soil with different initial water contents were studied by uniaxial tensile test in Tongcheng area of Hubei Province. The results showed that the initial moisture contents had a significant effect on the tensile strength of the collapsed soil. The characteristic curve of soil tensile strength appeared as a unimodal curve. The peak values were obtained at the water content of WC(24.4%) for the surface soil, laterite and red sand transition layer, while WC(25.8%) for the sandy layer. The axial and radial shrinkage lengths of different soil layers were positively correlated with the initial water contents, and the linear relationships between the axial and radial shrinkage of soil and the initial water contents were fitted with a higher correlation coefficient (the radial shrinkage of sand removal layer is exponentially correlated with the initial water contents). The mechanisms of water holding in soils with three initial water contents ranging from low (18%~22%), medium (22%~30%) to high (30%~saturation) was analyzed, which were soil capillary water holding mechanism, aggregate water bridge water holding mechanism and aggregate water holding mechanism respectively. These research results could provide a scientific basis for the scientific prevention and control of collapsed hill.