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Details of Grant 

EPSRC Reference: EP/D50631X/1
Title: Discrete element simulations of hollow cylinder testing of cohesionless soils
Principal Investigator: O'Sullivan, Dr C
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Department: Civil & Environmental Engineering
Organisation: Imperial College London
Scheme: First Grant Scheme Pre-FEC
Starts: 01 October 2005 Ends: 30 September 2008 Value (£): 115,709
EPSRC Research Topic Classifications:
Ground Engineering
EPSRC Industrial Sector Classifications:
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Summary on Grant Application Form
Soils and other granular materials (including food grains and pharmaceutical capsules) are made up of individual particles that can move relative to each other, rotate, and break. As a consequence of their particulate nature, the response of soils to applied loads is more complicated than the response of typical continuous materials (e.g. timber, steel). Understanding the response of soil to loadings is crucial to almost every construction project. Researchers know that aspects of soil behaviour (e.g. how much it deforms upon loading) is dependant on both the magnitude and the direction of the loads acting on the soil. Typically researchers develop their understanding of soil response by applying forces or loads to small samples of soil in the laboratory. Many of these tests cannot replicate the load conditions that the soil will feel during construction. One sophisticated testing apparatus that can obtain a good representation of the field loading conditions is the hollow cylinder apparatus (HCA). In the hollow cylinder apparatus a cylindrical sample of soil is simultaneously compressed and twisted. By controlling the applied loads and torques in this apparatus a relatively accurate replication of the field loading conditions can be obtained.Up until recent times, engineers who wanted to develop computer (mathematical) models of soil needed to assume that soil behaves as a continuous material. When soil is assumed to be continuous in a model, complicated equations and formulae are needed to describe the complexities of soil response that are a consequence of the particulate nature of soil. More recently an alternative approach to modelling soil, called discrete element modelling, has become popular. In this new approach the particulate nature of the soil is explicitly considered. The individual particles are themselves modelled and the contact forces that develop during loading can be calculated. Discrete element models can be used to visualize what is happening inside in the material and help researchers develop a detailed understanding of the particle - scale interactions that underlie the complex behaviour of the material as a whole.In any computer model certain simplifications of the real physical system must be made. The popularity of discrete element models is constantly increasing, so it is very important that researchers establish that the simplifications used in the model do not inhibit the model from giving relatively accurate results. In the proposed project, it is intended to carry out a series of hollow cylinder experiments and then simulate these experiments using a discrete element model. The results would allow us to determine how accurately a discrete element model can simulate the behaviour of granular materials under complex load conditions. Furthermore, the simulations will help us understand exactly what is happening to the material in the hollow cylinder apparatus and extend our understanding of the particle-scale interactions that govern soil response under a broader range of loading conditions than has previously been considered.
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