A Conceptual FEM-DEM Framework for Cyclic Stability of Unsaturated Retaining Walls

Milad Zakeri Ziyarati¹ Mahzad Esmaeili-Falak²

1) Ph.D. Student, Department of Civil Engineering, NT.C., Islamic Azad University, Tehran, Iran
2) Associate Professor, Department of Civil Engineering, NT.C., Islamic Azad University, Tehran, Iran

IOI Code : AAHF-ABKDBB
Publication : National Conference on Architecture and Art Technologies, Smart City, Soft and Creative Industries and Technological Culture(icact.ir)
Abstract :
    The long-term performance of retaining structures in unsaturated soils is significantly influenced by repeated wetting-drying (W-D) and freeze-thaw (F-T) cycles, which alter suction, hydraulic conductivity, and shear strength. Although numerous studies have individually investigated these phenomena, a unified framework coupling transient seepage with discrete crack evolution and interface degradation remains lacking. This paper introduces a conceptual coupled finite-element–discrete-element (FEM–DEM) framework designed to synthesize these effects into a cohesive assessment tool. Critically, this work does not present original computational outputs; rather, it offers a rigorously structured numerical architecture wherein cycle-dependent degradation functions calibrated against published laboratory data are systematically embedded. To verify the framework s internal consistency, published benchmark results from the recent literature and experimental data are re-interpreted within this conceptual model. The synthesized evidence indicates that the factor of safety may decline by over 50% after five severe climatic cycles, with conventional continuum methods yielding comparatively optimistic estimates. Additionally, a transition from deep-seated rotational failure to shallow translational sliding behind the retaining wall is identified. This conceptual framework underscores the necessity of explicitly modeling weather-induced cracking and suction dissipation, while full numerical implementation and validation are designated as future research phases.

Keywords : unsaturated soil retaining structure wetting drying and freeze thaw cycles fem dem coupling matric suction hydro mechanical degradation