Deformation coordination and stress analysis of slopes with concrete toe and flexible facing slab using FDEM

Abstract

This study investigates a novel slope support system comprising a concrete toe and a flexible facing slab, characterized by soil–structure interaction and deformation coordination. Using the finite-discrete element method (FDEM), a mechanical framework accounting for continuous–discontinuous deformation conversion is established to investigate the deformation coordination and stress characteristics of the system under normal service conditions. A hybrid discretization strategy is adopted: the toe is modeled as linear elastic finite elements, the soil with Mohr–Coulomb elastoplasticity, and the slab via discrete elements. A refined model with unstructured third-order finite element meshes and polyhedral particles is developed, using the birth-death technique for staged construction. Model validation includes analytical benchmarking for in-situ stress equilibrium and qualitative comparison with published experimental observations. Parametric studies systematically examine the effects of toe stiffness, slab thickness, contact properties, and loading conditions on system response. The mechanical behavior is interpreted through displacement field evolution, stress distribution in the flexible slab, load-transfer mechanisms in the toe, and rigid–flexible component interaction. Results indicate that the slab relieves earth pressure via a membrane effect, producing a nonlinear back-pressure distribution, while the toe provides rigid restraint against lateral displacement and sustains the predominant lateral load. This study offers theoretical guidance for the design of such composite support slopes under the conditions analyzed, while recognizing that further validation and broader parametric studies are required before general design recommendations can be formulated.