Coupled influence of particle shape and basal configuration on rheology of granular media impacting against slit dam

Particle shape and basal boundary conditions play a crucial role in determining mobility, deposition, and impact response of granular flows; yet their coupled influence remains largely unexplored. To this end, we investigate rheology of dry granular media interacting with slit dam within a 3D discrete element setting with varying grain shapes and basal configurations. Besides spherical particles, we consider Platonic solids, viz., dodecahedron, octahedron, and tetrahedron, to explicitly isolate influence of particle morphological features, e.g., sphericity ( ψ ), as these shapes possess identical convexity and aspect ratio while differing primarily in various sphericity measures. Furthermore, we vary basal slip using plane smooth (PS), plane rough (PR), and undulated rough (UR) basal configurations. Comprehensive examination of flow kinematics, kinetics, and grain-scale signatures reveals that decreasing ψ suppresses flow mobility through enhanced particle interlocking and restricted rotation, thereby increasing residual force on barrier. With increasing basal roughness from PS to PR followed by UR, basal slip reduced, accompanied by energy dissipation. Analyses of granular temperature, shear rate, coordination number, force-chain evolution, and fabric anisotropy reveal micromechanical origins of observed macroscopic responses. Additionally, dynamic pressure coefficient ( k d ) scales with Froude number, which varies with ψ for different basal configurations via its control on flow velocity and depth, a relationship developed herein across sphericity measures. Interestingly, k d exhibits maximum value for UR configuration despite exhibiting lowest peak impact force resulting from moderate flow depth and velocity. The micro -to– macro insights further aid in improving impact-force prediction, thereby promoting enhanced design of landslide mitigation structures.