Constitutive and numerical modelling of wet granular flow and deformation

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The proposed research focuses on the development of computer modeling capabilities in analyzing soil mobility and movement. Ground movement and soil mobility are important subjects in geotechnical engineering. Small and large movements are of important interest, and sometimes crucial, for many engineering projects. Large movement and fast mobility of soil, such as landslides and debris flow, threaten human safety and cause property damage. As a result, a quantitative risk analysis (QRA) has been adopted to determine potential threats due to these natural hazards. In QRA, it is necessary to analyze soil movement and soil mobility with reasonable accuracy and reliability.There are two approaches in analyzing soil movement and mobility: continuum and discontinuum (discrete) approaches. The continuum approach has been extensively used in analyzing small to moderate movement. When soil is in motion, there is considerable mixing of the material which cannot be modelled effectively by using the continuum approach. There are partings and separations of the material when it undergoes shear failure. The discrete approach can handle these situations more effectively. However, it is difficult to take water into consideration in discrete modelling. Water has an effect on the inter-granular forces since it exerts pressure on the surfaces of the grains. Under high solid concentration flow, movement of water imposes drag forces on individual grains which result in grain movements. On the other hand, the presence of soil particles changes the flow pattern. This is called two way solid-fluid coupling. Water flow can be induced by pressure gradients due to solid deformation and changes in the void space. However, water flow will result in changes in pore pressure which in turn causes deformation. This is a solid deformation-fluid coupling problem. The calculation of pore pressure and intergranular forces changes is not trivial in discrete modelling since discrete modelling only models individual grains and not the pore space. This research is focused on improving the numerical techniques to incorporate water in discontinuum modelling. The model is based on a combined continuum and discontinuum approach in modelling fluid and solid. Also, it is important to be able to determine the micromechanics parameters for discrete modelling. This research will examine the relationship between micro and macro material parameters in order to provide realistic model parameters for discontinuum modelling. This research is important and applicable to many fields in engineering and science that involve interaction between fluid and granular material such as sediments analysis in rivers, hydrotransport, debris flow and geohazard management, filtration in soils, sand production in oil wells etc. Many of these areas are important issues in Canada related to oil extraction, river sediments and geohazard managements.