Research Status and Prospect of Highway Bedding Slope Stability in Sichuan Mountain Areas

In response to the complex failure mechanisms of bedding slopes along highways in Sichuan mountain areas, which pose significant threats to engineering construction and operational safety, this study systematically reviews recent research achievements from four aspects: failure characteristics under lateral constraints, strength properties of slip zone soils, determination of the initial instability length, and stability evaluation, while proposing future research directions. The results show that: (1) For bedding slopes under lateral constraints, the primary sliding direction often deviates from the dip direction of rock strata, necessitating further investigation into the determination of sliding forces and the classification of bedding slopes in multi-face free-surface environments. (2) Research on the strength properties of slip zone soils should prioritize undisturbed samples, with shear strength parameters obtained through large-displacement shear tests (e. g., ring shear tests), complemented by analyzing material composition and mesostructure. (3) The initial instability length can be determined via numerical simulation by integrating plastic zone characteristics, stress distribution, and displacement patterns at the basal sliding surface. Theoretical approaches rely on stress state partitioning along the slip surface, while empirical formulas derived from statistical analysis offer greater practicality. However, further investigation is required regarding the influence of the angle between rock strata and slope strike, as well as the rationality of coefficients in regression models. (4) Stability evaluation of retrogressive progressive failure in bedding slopes depends on strain-softening analysis of slip zone soils. The constitutive relationship governing strain-softening behavior serves as the cornerstone for both numerical modeling and theoretical derivation. Refined characterization of strain-softening processes will enhance the precision of stability assessments.