Discrete Element Modelling of Recycled Waste Rock under Monotonic Loading

T. Afshar, M.M. Disfani, A. Arulrajah, G.A. Narsilio

In the proceedings of: GeoRegina 2014: 67th Canadian Geotechnical Conference

Session: Transportation Geotechnics

ABSTRACT: lement Modelling of Recycled Waste Rock under Monotonic Loading T. Afshar, M. M. Disfani & A. Arulrajah Department of Civil & Construction Engineering, Faculty of Science, Engineering & Technology Œ Swinburne University of Technology, Melbourne, Victoria, Australia G. A. Narsilio Department of Infrastructure Engineering Œ The University of Melbourne, Melbourne, Victoria, Australia ABSTRACT The mechanical and particle scale responses of a recycled Construction and Demolition (C&D) material being crushed basaltic Waste Rock (WR) under monotonic loading was investigated using a series of Discrete Element Method (DEM) simulations of biaxial shear strength tests. Previous laboratory and field experiments have proven the viability of this crushed waste rock as a pavement subbase material. This study offers a brief review of previous work on DEM modelling of granular materials with particular focus on simulation of particle shape and particle breakage. In addition, this paper studies the rich particle scale information provided in the DEM simulation to develop further understanding of the waste rock behaviour. A good agreement was found between the predictions of the numerical analyses and the available experimental results in terms of macro-mechanical responses. The results confirm that particle properties have a significant effect on the soil stress-strain behaviour. RÉSUMÉ L'étude analyse les propriétés mécaniques et la nature des particules obtenues à partir de débris recyclés par construction et démolition (C&D). Ces matériaux, composés de déchets rocheux granulaires basaltiques sous régime monotone, ont été examinés par une série de modélisations - Méthode des Éléments Discrets (DEM) - en résistance au cisaillement bi-axial. Les expérimentations préliminaires faites en laboratoires et sur les sites naturels ont prouvés la viabilité de ces agrégats concassés en tant que matériaux d'embase pour chaussées. Cette présente étude offre tout d'abord un bref rappel des résultats antérieurs obtenus par modélisation DEM de matériaux granuleux. Cette analyse s'intéresse particulièrement aux simulations effectuées sur la nature du milieu granulaire (forme et rupture). Ainsi, l'étude de la distribution de tailles des particules issue par simulation DEM amène à une meilleure compréhension des propriétés de déchets granulaires. Une parfaite corrélation fut trouvée entre les prédictions numériques et les résultats expérimentaux en termes de réponse macro-mécanique. Les résultats confirment que les propriétés des particules ont un effet significatif sur le comportement contraintes-déformations du terrain. 1 INTRODUCTION Discrete Element Method (DEM) is a numerical modelling approach that can simulate granular materials taking into account particle interactions. DEM models simulating laboratory tests also play an important role in advancing our understanding of the mechanics of granular material response, including bonded or cemented particulate materials (O'Sullivan 2011). The use of traditional road building materials at the current rates of consumption is unsustainable from both environmental and cost perspectives. Consequently, the sustainable application of recycled materials has received increasing research interest. Recycled Construction and Demolition (C&D) materials have traditionally been considered waste material in Australia. There exists now a developing emphasis on sustainable environmental management that has resulted in growing pressure to investigate the viability of reusing all categories of waste material, including C&D materials. C&D material is the excess or waste material associated with the construction and demolition of buildings and structures. C&D materials which are of interest in relation to pavement applications include bricks, concrete, crushed rock, and reclaimed asphalt. C&D industries generate 40% of all waste going to landfill, despite the fact that these materials can be used as alternatives to quarry based products for roads, footpaths, and a range of other roadwork applications (Arulrajah 2012; Disfani et al. 2012). In this study, the macro-mechanical and particle scale responses of crushed Waste Rock (WR) under monotonic loading will be investigated using a series of DEM simulations with PFC2D (Particle Flow Code). 2 DISCRETE ELEMENT MODELLING OF GRANULAR MATERIALS DEM is a numerical tool based on the interaction of individual particles. Particle shape and grain breakage, among other factors, affect the accuracy of a DEM modelling (O'Sullivan 2011). These are briefly discussed here. 2.1 Particle breakage phenomenon Since the original DEM introduced by Cundall et al. (1979) did not consider particle breakage, different methods have been proposed to overcome this restriction. One solution to this problem is to treat each granular particle as an agglomerate built by bonding smaller particles. In order to establish a failure criterion, the strength of the bond between the particles shaping the agglomerates needs to

RÉSUMÉ: ete Element Modelling of Recycled Waste Rock under Monotonic Loading T. Afshar, M. M. Disfani & A. Arulrajah

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T. Afshar; M.M. Disfani; A. Arulrajah; G.A. Narsilio (2014) Discrete Element Modelling of Recycled Waste Rock under Monotonic Loading in GEO2014. Ottawa, Ontario: Canadian Geotechnical Society.

@article{GeoRegina14Paper236,author = T. Afshar; M.M. Disfani; A. Arulrajah; G.A. Narsilio,title = Discrete Element Modelling of Recycled Waste Rock under Monotonic Loading,year = 2014}