A particle-based method for fine granular flow and degradation analysis with an elastic–perfectly plastic Drucker–Prager law

We present a Moving Particle Hydrodynamics (MPH) solver for granular flows that couples a fully Lagrangian formulation with an elastoplastic constitutive law. Stresses are advanced using the Jaumann objective rate; plastic strain follows a standard flow rule; yielding is governed by the Drucker–Prager criterion. The governing equations are discretized via MPH particle–interaction models and integrated explicitly to update stress, velocity, and position. The method is validated against three benchmarks: (i) static granular dam-break with uniform grains, (ii) large-scale landslide, and (iii) jet impingement and packing in a rectangular container. In dam-break tests, simulations reproduced the angle of repose sharply and exposed internal stress fields inaccessible to measurement; spreading-length discrepancies suggest that tuning Young's modulus and Poisson's ratio—used here as calibration parameters—can further improve accuracy, with angles of repose within ±20 % of measurements. Landslide simulations captured overall behavior across particle-size ranges and aspect ratios; agreement was strongest for finer grains, while deviations at smaller nominal sizes likely reflect unmodeled packing-fraction effects that reduce effective bulk friction. In the impingement–packing case, the computed bed shape and repose angles matched experiment and DEM, with angles within ±10 %. These results indicate that elastoplastic MPH provides a practical, scalable alternative to DEM for large-deformation, size-heterogeneous granular flows. • A physically consistent granular-flow formulation based on Moving Particle Hydrodynamics (MPH) with unified treatment of dense, highly deformable regimes. • Objective stress update using the Jaumann rate, Drucker–Prager yielding, and a plastic strain potential, allowing accurate prediction of granular collapse and deposition. • Extensive validation and benchmarking demonstrating strong agreement and competitive performance relative to DEM. • A unified scheme that handles irregular particle shapes and heterogeneous size distributions—situations where conventional DEM often struggles—without bespoke meshing or contact tuning.