Discrete Element Models Advance Slope Stability Analysis by Resolving Micro-Scale Mechanics

Slope failures rank among the most destructive geohazards worldwide, threatening human lives and infrastructure while inflicting severe and lasting ecological damage. Beyond immediate structural impacts, slope collapses cause the destruction of arable soil and vegetation cover, induce watercourse blockage and contamination, accelerate downstream sedimentation, and disrupt fragile coastal and mountain ecosystems. Reliable stability assessment represents both a critical engineering objective and an urgent environmental priority. Over the past two decades, the Discrete Element Method (DEM) has developed into a robust complement to conventional continuum methods for assessing slope stability. Unlike traditional continuum frameworks such as the Finite Element Method (FEM), discrete element simulations provide direct numerical access to fundamental grain-scale mechanisms, including interparticle bond breakage, fabric evolution, force chain reorganisation, and progressive failure processes that continuum formulations struggle to capture.

A critical review by Marwane Hammouti and colleagues systematically examines the theoretical foundations, contact constitutive laws, and micro-to-macro calibration strategies that govern DEM applications across geotechnical slope engineering. The investigation assesses particle dynamics formulations and contact constitutive models tailored specifically for granular sands, cemented rock masses, and cohesive clays. Bridging the gap between microscopic particle interactions and macroscopic soil response requires rigorous calibration strategies. The review details the continuum of contact models spanning from classical Hertz–Mindlin elastic contact formulations to the Parallel Bond Model (PBM) for cemented assemblies, alongside advanced critical-state soil mechanics representations including the Modified Cam-Clay (MCC) framework.

A central theoretical focus of the review is the micro-scale reformulation of the widely used Shear Strength Reduction (SRM) technique. By implementing an exact micro-to-macro mapping based on Bolton’s stress-dilatancy relationships, the researchers demonstrate that proportionally decreasing contact friction at the particle level does not produce an equivalent proportional reduction in macroscopic soil shear strength. Importantly, the analysis reveals that the mathematical sign of the discrepancy between microscopic and macroscopic safety factors is fundamentally state-dependent rather than universal.

For cohesive bonded materials, the review highlights an advanced damage-dependent constitutive framework designed to capture progressive degradation. Within this formulation, material cohesion and contact friction mobilise at separate, distinct stages of bond damage rather than simultaneously. The authors introduce an explicitly multivariable safety-factor mapping for bonded assemblies, cautioning against assigning an arbitrary or universal sign to stability adjustments.

To overcome the intense computational demands inherent to grain-scale calculations, the survey explores high-performance computational techniques, including GPU-accelerated computing architectures and hybrid multi-scale DEM–FEM frameworks.

Despite significant computational and theoretical progress, the survey identifies seven critical open challenges in current DEM research. Foremost among these limitations is the persistent lack of a standardised calibration protocol for implementing Modified Cam-Clay critical-state models within cohesive soil simulations.

To evaluate current capabilities and practical limitations, the authors examine a macro-scale proof-of-concept back-analysis of a documented natural landslide located in northern Morocco. Ultimately, the review establishes a detailed technical roadmap for geotechnical specialists seeking to balance discrete micro-mechanical resolution with the strict reliability requirements of engineering practice, defining the exact modeling conditions under which DEM genuinely captures grain-scale mechanics rather than merely functioning as an inefficient proxy for continuum methods.

Subject of Research: Discrete element modeling applications, micro-mechanical contact laws, and calibration frameworks for geotechnical slope stability

Article Title: An overview of discrete element modeling for slope stability

Article References: Hammouti, M., El Haim, M., Medini, M., Bensaid, M., Ahsayen, M., & Morabit, A. (2026). An overview of discrete element modeling for slope stability. Discover Materials. https://doi.org/10.1007/s43939-026-00998-5

Image Credits: AI Generated

DOI: 10.1007/s43939-026-00998-5

Keywords: discrete element method, slope stability, shear strength reduction, finite element method, geohazards, landslides, force chain reorganisation, fabric evolution, parallel bond model, modified cam-clay, hertz-mindlin contacts, bolton micro-to-macro mapping, cohesive soils, gpu acceleration, machine learning surrogates, hydro-mechanical coupling, progressive failure