Discrete element modelling of the resilient behaviour of unbound granular aggregates

Abstract

The scope of this study is to use a three-dimensional discrete element model to simulate the resilient response of an unbound granular material subjected to sinusoidal loading in a triaxial sample and to compare the simulated results to experimental results. A three-dimensional discrete element model, where each grain interacts with its neighbour grains, allows a micromechanical approach to modelling. By doing the sensitivity analysis on the input parameters the model can be evaluated and insight gained about the factors that affect the resilient behaviour. Uniform spherical grains were used in both the DEM simulations and in the triaxial experiments. Two contact models, linear visco-elastic and Hertzian, and two types of confinement, a uniform cylinder and a flexible membrane, are tested in the simulations. Comparison of the simulation results with the results of similar laboratory experiments shows that the discrete element approach is suitable to model idealised aggregate grains.

Keywords:

• unbound granular aggregates
• cyclic load triaxial testing
• resilient modulus discrete elements
• contact models

Acknowledgements

The authors would like to acknowledge the valuable advice contributed by Dr John Peters and Dr Steven Grant at the US Army Corps of Engineers Engineering Research and Development Centre (ERDC) Geotechnical and Structures Laboratory and Cold Regions Research and Engineering Laboratory, respectively.

The laboratory and computational work was supported by the six participants of the Norwegian GARAP (Granular Aggregates in Road and Airfield Pavements) project: Norwegian Public Roads Administration; Norwegian Rail Administration; The Research Council of Norway; Norwegian Aggregate Producers Association; Avinor; Nynäs.

Computational model development was supported by a grant from the US Army Corps of Engineers ERDC Military Engineering Basic Research Programme.