A shear constitutive model for describing the full process of the deformation and failure of slip zone soil

The shear mechanical behaviour of slip zone soil is of great significance for the stability analysis of landslides. Based on the shear deformation-failure characteristics of slip zone soil and the statistical damage theory, a shear constitutive model is proposed to describe the shear stress - displacement relation of slip zone soil. Parameters in the proposed model have clear physical-mechanical meaning, and can be easily obtained by shear tests. The shear constitutive model is verified by comparing model results with ring-shear test results on the slip zone soil from the Huangtupo landslide in the Three Gorges Reservoir Area of China. It reveals that the model is capable of capturing the salient behaviour of the slip zone soil, such as the pre-peak and post-peak deformation characteristics. Moreover, utilizing limited ring-shear test data under given normal stresses, shear stresses at various shear displacements under untested normal stress are available by this model. Finally, a dynamic evaluation method of landslide stability, which incorporates the landslide displacement by presented constitutive model, is proposed and applied to analyze the stability of the Riverside Slump II# of the Huangtupo Landslide.