An Experimental Determination of the Inter-particle Contact Behaviour of Sands

Description

Discrete Element Analyses are now used extensively in Soil Mechanics, but the contact models that are used for sands under quasi-static loading are relatively simple and are based on surprisingly little data. The aim of the research is to provide the first comprehensive set of data investigating the contact mechanics of sand particles. The proposed research builds on earlier work by the applicants at Imperial College and currently at the City University of Hong Kong in constructing apparatus suitable for such an investigation. Limited previous experiments by the applicants led to the unexpected finding that for soils the normal load-deflection behaviour was dominated by plasticity at very small loads, not elasticity as assumed in the simple models typically used, even if similar behaviour had been seen previously in other materials. However, very little remains known about most key aspects of contact behaviour, and these will be the focus of this research. Perhaps most notable amongst the areas of uncertainty for soils is the behaviour under tangential loading and the interaction of tangential and normal loads. The project will also examine the effects of rate of loading and repeated loading, the influence of pore fluid on contact behaviour and the changes to the morphology of the particles that are caused by contact loading. Most existing work has been restricted to a very narrow range of particle types and so a key objective of the research will be to broaden the sands tested, covering a wide range of mineralogies and particle types and sizes.