Deformation Viscosity Effect and Stability Influencing Factors Sensitivity Analysis of Slope with Soft Interlayer

Abstract Empirical evidence indicates that the strength of plastic flow toward the slope surface, resulting from the compression of a soft interlayer between upper and lower hard rock layers, increases with the thickness of the soft interlayer. Consequently, this study introduces the concept of the deformation viscosity effect in slopes containing soft interlayers, elucidating its underlying mechanism based on the presence of a constraint reaction force at the interface between soft and hard rock layers. Through finite element analysis of the Guiyang bank slope of the Huayudong Bridge, the objective existence of the viscosity effect is demonstrated, and its evolutionary behavior is examined. Additionally, the sensitivity of five key geometric and mechanical parameters of the soft interlayer on slope stability is quantitatively assessed using a composite algorithm that integrates range analysis, Grey Relational Analysis (GRA), and Analytic Hierarchy Process (AHP). The findings reveal that the sensitivity of factors affecting the stability of the Huayudong Bridge Guiyang bank slope is ranked as follows: inclination angle > cohesion > internal friction angle > thickness > weight. The analytical results provide valuable insights for the effective prevention and control of slopes with soft interlayers.