A micromechanical study of shear-weakening characteristics of granular flow in a torsional shear cell
Computers and Geotechnics, 189:107591, 2026.
Summary
Discrete element simulations are used to connect granular shear weakening with changes in particle-scale force networks. A torsional shear cell is examined across quasi-static, transitional, and grain-inertial flow regimes. Two configurations with slightly different initial packing densities provide a comparison of macroscopic stresses and internal force-chain evolution. Modified constitutive relations describe the measured stress trends, while microscopic analyses track chain length, abundance, curvature, orientation, and load distribution. The results show that these characteristics evolve differently across regimes and depend differently on the initial packing state. Changes in force-chain number and anisotropy help distinguish configurations with stronger transitional shear weakening. Curvature is less sensitive to packing density and stress, suggesting that it more directly reflects structural rearrangement. The study therefore links macroscopic constitutive behavior with selected microscopic indicators rather than attributing weakening to a single universal force-network measure.