Mechanistic modelling of tests of unbound granular materials

Abstract

Various tests are used to characterise the strength and resilience of granular materials used in the subbase of a pavement system, but there is a limited understanding of how particle properties relate to the bulk material response under various test conditions. Here, we use discrete element method (DEM) simulations with a mechanistically based contact model to explore influences of the material properties of the particle on the results of two such tests: the dynamic cone penetrometer (DCP) and the resilient modulus tests. We find that the measured resilient modulus increases linearly with the particle elastic modulus, whereas the DCP test results are relatively insensitive to particle elastic modulus. The DCP test results are also relatively insensitive to inter-particle friction coefficient but strongly dependent on the particle shape. We discuss strengths and weaknesses of our modelling approach and include suggestions for future improvements.

Keywords::

• granular bases
• unbound materials
• resilient modulus
• dynamic cone penetrometer
• discrete element method

Acknowledgements

The authors gratefully acknowledge helpful conversations with John Siekmeier and Lee Amundson of the Technical Advisory Panel and funding from MN-DOT and LRRB through project #1573.