Systematic description of the effect of particle shape on the strength properties of granular media

¹ LMGC, Université de Montpellier, Montpellier, France
² Departamento de Ingeniería Civil y Ambiental, Universidad de Los Andes, Bogota, Colombia
³ Department of Mechanical Engineering, Faculty of Engineering, Chiang Mai University, 239 Huay Kaew Rd., Chiang Mai 50200, Thailand
⁴ INRA, UMR IATE Montpellier
⁵ LMGC, Université de Montpellier, Montpellier, France / 〈MS E〉 2, UMI 3466 CNRS-MIT, MIT Energy Initiative, 77 Massachusetts Avenue, Cambridge 02139, USA

^* e-mail: emilien.azema@umontpellier.fr
^** e-mail: n.estrada22@uniandes.edu.co
^*** e-mail: itthichai.p@cmu.ac.th
^**** e-mail: jean-yves.delenne@umontpellier.fr
^† e-mail: e-mail: franck.radjai@umontpellier.fr

Published online: 30 June 2017

Abstract

In this paper, we explore numerically the effect of particle shape on the mechanical behavior of sheared granular packings. In the framework of the Contact Dynamic (CD)Method, we model angular shape as irregular polyhedral particles, non-convex shape as regular aggregates of four overlapping spheres, elongated shape as rounded cap rectangles and platy shape as square-plates. Binary granular mixture consisting of disks and elongated particles are also considered. For each above situations, the number of face of polyhedral particles, the overlap of spheres, the aspect ratio of elongated and platy particles, are systematically varied from spheres to very angular, non-convex, elongated and platy shapes. The level of homogeneity of binary mixture varies from homogenous packing to fully segregated packings. Our numerical results suggest that the effects of shape parameters are nonlinear and counterintuitive. We show that the shear strength increases as shape deviate from spherical shape. But, for angular shapes it first increases up to a maximum value and then saturates to a constant value as the particles become more angular. For mixture of two shapes, the strength increases with respect of the increase of the proportion of elongated particles, but surprisingly it is independent with the level of homogeneity of the mixture. A detailed analysis of the contact network topology, evidence that various contact types contribute differently to stress transmission at the micro-scale.