3D DEM simulations of monotonic interface behaviour between cohesionless sand and rigid wall of different roughness

Abstract

The paper deals with three-dimensional simulations of a monotonic quasi-static interface behaviour between cohesionless sand and a rigid wall of different roughness during wall friction tests in a parallelly guided direct shear test under constant normal stress. Numerical modelling was carried out by the discrete element method (DEM) using spheres with contact moments to approximately capture a non-uniform particle shape. The varying wall surface topography was simulated by a regular mesh of triangular grooves (asperities) along the wall with a different height, distance and inclination. The calculations were carried out with different initial void ratios of sand and vertical normal stress. The focus was to quantify the effect of wall roughness on the evolution of mobilized wall friction and shear localization, also to specify the ratios between slip and rotation and between shear stress/force and couple stress/moment in the sand at the wall. DEM simulations were generally in good agreement with reported experimental results for similar interface roughness. The findings presented in this paper offer a new perspective on the understanding of the wall friction phenomenon in granular bodies.

Comparative 3D DEM simulations of sand–structure interfaces with similarly shaped clumps versus spheres with contact moments

“…The interface behaviour between granular materials and structures has been investigated using various testing devices and methods (see the overview in [15]), mainly with the aid of interface direct shear apparatuses (e.g. [5-9, 17, 19, 42-44, 48, 50, 52, 58, 70, 72]).…”

“…The critical normalized roughness was mainly about 0.40-0.50 and above this value, the maximum interface friction angle insignificantly increased. The literature overview on the interface behaviour between cohesionless sand and rigid wall of different roughness with respect to numerical solutions within continuum mechanics and discrete mechanics was given in [15]. There exist many DEM studies of sand-structure interfaces under 2D (e.g.…”

“…[13,14,16,22,64,65,74]) and 3D conditions [12,15,24,69,73]. In those studies, disks with contact moments were used in 2D simulations [13,14,16,22,64,65,74] or spheres with contact moments were used in 3D simulations [12,15,24,69]. The clumps were either assumed in 2D [22] or 3D simulations [73].…”

“…It was shown that the rolling resistance model was limited in its ability to capture particle shape effects [71]. The existing DEM simulations also exhibited a bi-linear relationship between the interface resistance and normalized interface roughness [15,24,69,73]. The critical normalized roughness was found to be in 3D studies about 0.40-0.75 [15,24,69,73].…”

“…In our earlier paper [15], the monotonic quasi-static interface behaviour between cohesionless sand and a rigid wall of different surface topography using a direct shear box under conditions of constant normal stress was comprehensively analysed using 3D DEM (the particle-based open-source code YADE). To approximately simulate the irregularity of sand particles' shape of 'Karlsruhe' sand, spheres with contact moments were used.…”