Constitutive and numerical modelling of wet granular flow and deformation

提出的研究重点是发展分析土壤流动性和运动的计算机建模能力。地面运动和土壤流动性是岩土工程中的重要课题。对于许多工程项目来说，大小运动都是非常重要的，有时甚至是至关重要的。山体滑坡、泥石流等土体运动大、流动性快，威胁人身安全，造成财产损失。因此，采用定量风险分析（QRA）来确定这些自然灾害造成的潜在威胁。在QRA中，需要以合理的精度和可靠性分析土壤运动和土壤迁移性。分析土壤运动和流动性有两种方法：连续统和非连续统（离散）方法。连续体方法已广泛用于分析小到中度运动。当土壤处于运动状态时，会有大量的物质混合，这是用连续体方法无法有效模拟的。材料在剪切破坏过程中会出现分离和分离现象。离散方法可以更有效地处理这些情况。然而，在离散建模中很难考虑水的影响。***水对颗粒间力有影响，因为它对颗粒表面施加压力。在高浓度固相流下，水的运动对单个颗粒施加阻力，导致颗粒运动。另一方面，土壤颗粒的存在改变了流动模式。这被称为双向固流耦合。由于固体变形和空隙空间的变化而产生的压力梯度可引起水流。然而，水流会引起孔隙压力的变化，从而引起变形。这是一个固体变形-流体耦合问题。在离散模型中，孔隙压力和晶间力变化的计算并不简单，因为离散模型只模拟单个颗粒，而不是孔隙空间。***本研究的重点是改进数值技术，将水纳入非连续介质模拟。该模型基于连续统和非连续统相结合的方法来模拟流体和固体。此外，能够确定离散建模的微观力学参数也很重要。本研究将探讨微观和宏观材料参数之间的关系，以便为非连续体建模提供真实的模型参数。***本研究在涉及流体与颗粒物质相互作用的许多工程和科学领域具有重要的应用价值，如河流沉积物分析、水运、泥石流和地质灾害管理、土壤过滤、油井出砂等。在加拿大，许多这些地区都是与石油开采、河流沉积物和地质灾害管理有关的重要问题。

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.