A Hybrid FLAC3D-MPM Approach for Post-Failure Slope Behavior

Summary

Abstract

Simulating large-strain behaviour in rock slopes poses significant challenges for traditional continuum modelling methods, primarily due to mesh distortion leading to numerical instabilities. While mesh remeshing can mitigate this issue, it becomes computationally intensive and technically complex in 3D, especially for irregular geometries. Meshless methods such as the Material Point Method (MPM) and Smoothed Particle Hydrodynamics (SPH) offer an alternative by avoiding mesh distortion entirely; however, they often come with drawbacks including longer run times and difficulty applying boundary conditions. This paper presents a hybrid modelling approach that combines the efficiency of a finite-volume meshed continuum with the flexibility of MPM for simulating large deformations. The model uses traditional finite-volume zones in regions of low strain, while areas expected to undergo large deformation are handled with material points. The interface between the two domains allows for information transfer through an overlapping region. Material point regions can be defined at the outset or generated dynamically when deformation thresholds are exceeded, enabling a responsive and efficient modelling framework. To evaluate performance, a rock slope failure with significant runout is simulated using three configurations: fully meshed (FLAC3D), hybrid FLAC3D-MPoint, and fully meshless (MPoint). Displacement patterns and computational times are compared across all cases. This hybrid formulation is particularly relevant for risk and reliability assessments of rock slopes, where post-failure deformation and runout are critical to consequence estimation. By capturing large displacements without compromising computational efficiency, this approach improves runout predictions and supports risk-informed slope design.