Micro-mechanical modelling of unsaturated packings using CFD-DEM and computed tomography (MIME-UP)

该项目的主要目的是研究部分饱和砂土中毛细效应对其力学和水力特性的影响。因此，计划在X射线断层扫描仪中进行数值模拟和微尺度实验。对于部分饱和砂土的数值模拟，将使用解析的CFD-DEM。现有的方法将补充两相流公式考虑孔隙水和孔隙空气的影响。在X射线断层扫描仪中进行的微尺度实验将用于验证新开发的模型。特别注意的是，因此，在去饱和的砂柱以及在三轴试验中的变形行为和载荷响应期间的毛细桥的形成。为此，颗粒之间的相互作用的计算，流体和变形，负载响应膜将在解决CFD-DEM的框架内开发。在一个可能的延长两年，非饱和三轴试验将在CT断层扫描仪进行，以了解砂的水力力学行为。第一个资助期开发的工具将被合并并扩展到模拟非饱和三轴试验。为了达到既定目标，汉堡理工大学/德国和DCS计算林茨/奥地利之间的合作计划。DCS正在开发用于研究项目的代码CFDEM耦合。这一合作由D-A-CH协议（德国的DFG和奥地利的FWF）涵盖。

The main objective of the proposed project is to investigate the influence of capillary effects in partially saturated sands on their mechanical and hydraulic behaviour. Therefore, numerical simulations as well as micro-scale experiments in an x-ray tomograph are planned. For the numerical simulation of partially saturated sands, the resolved CFD-DEM will be used. The existing method will be supplemented by a two-phase flow formulation to consider the influence of pore water and pore air. The micro-scale experiments performed in the x-ray tomograph will be used to validate the newly developed models. Special attention is thereby paid to the formation of capillary bridges during desaturation of a sand column as well as the deformation behaviour and load-response in a triaxial test. For this purpose, the computation of the interaction between particles, fluid and a deforming, load-responsive membrane will be developed in the framework of resolved CFD-DEM. In a possible extension of two years, unsaturated triaxial tests will be conducted in the CT-tomograph to understand the hydro-mechanical behaviour of sand. The developed tools of the first funding period will be combined and extended to model unsaturated triaxial tests.To reach the defined objectives a co-operation between Hamburg University of Technology/Germany and DCS Computing Linz/Austria is planned. DCS is developing the code CFDEMÒcoupling, which is used in the research project. This cooperation is covered by the D-A-CH agreement (DFG in Germany and FWF in Austria).