Parametric study of a loess slope based on unified strength theory

The unified strength theory takes into consideration the effects of intermediate principal stress, and a series of yield surfaces can be determined using various values of parameter b which reflects the effects of the intermediate principal stress. The lower bound (obtained using b = 0.0) is the widely used Mohr-Coulomb failure law, and the upper bound (obtained using b = 1.0) is generalized as the twin-shear strength theory. In this study, a combination of a physical model experiment and numerical simulations using unified strength theory is used to analyze the influence of b on the failure and stability of a loess slope. An analysis shows that the size of the computed failure zone decreases noticeably with an increase in b. In contrast, the factor of safety (FOS) of the slope increases linearly with an increase in b, and an increase of 23-25% in the FOS can be obtained using b = 1.0 as compared to that for b = 0.0. A comparison of the physical model experiment and simulation shows that the range of b = 0.25-0.50 is valid for determining the failure characteristics and stability of the experimental loess slope.