Numerical Modelling for Fresh Concrete and Deep Foundation Construction

在过去的十年中，混凝土外加剂的快速发展及其在预拌混凝土中的越来越多的使用从根本上改变了导管混凝土的设计。对强力化学品的依赖使新浇混凝土的性能和行为对其成分、混合和工艺非常敏感，导致深基础施工中出现各种故障，这对受影响的基础设施项目可能是灾难性的。为了解决这些问题，该项目旨在研究新浇混凝土的流动行为及其与支撑流体和周围土壤形成的复杂相互作用，通过开发新的数值工具，帮助理解在全尺寸深基础施工的背景下，导管混凝土的多相物理。该项目将系统地调查混凝土性能、基础设计、施工过程和完工质量之间的关系，其中特别关注钢筋设计的影响、混凝土混合物的可变性以及支撑液的性能和现场条件。深基础施工过程涉及三个材料系统：土壤、支撑液和导管混凝土，每一个都是以其自身形式存在的多相材料。复杂的多物理相互作用同时存在：地层失水、土粒冲刷、土、水泥浆和支护液混合形成的界面层、混凝土拌合物泌水、粗骨料离析、墙面形成滤饼等，都影响深基础的成桩质量，目前的知识还没有充分理解这些问题，因此各种项目的补救费用很高。拟议的项目是与LUSAS合作，LUSAS是英国领先的数字工具开发商。这项新的合作将通过一个新的维度增加一个关键的权重，将以前和正在进行的研究提高到高TRL水平。

Over the past decade, the rapid development of concrete admixtures and their increasing use in ready mixed concrete has fundamentally changed the design of tremie concrete. The dependence on powerful chemicals makes the properties and behaviours of fresh concrete sensitive to its composition, mixing and workmanship, resulting in various failures in deep foundation construction, which can be catastrophic to the infrastructure project affected. To address these issues, this project aims to study the flow behaviour of fresh concrete and its complex interactions with support fluid and surrounding soil formation, by developing novel numerical tools that help to understand the multiphase physics of tremie concrete in the context of full-scale deep foundation construction. The project will systematically investigate the relationship between concrete properties, foundation design, construction processes and completion quality, where a special focus is on the impact of reinforcement design, the variability of concrete mixes and the properties of support fluid and site conditions. The process of deep foundation construction involves three material systems: soil, support fluid and tremie concrete, each of which is a multiphase material in its own form. Complex multi-physics interactions are simultaneously present: fluid loss into the soil formation, soil particles washing out, interface layer formed by the mixture of soil, cement paste and support fluid, water bleed from the concrete mix, coarse aggregates segregation, formation of filter cake on the wall surface, etc. All of these affect the completion quality of deep foundation, which are not adequately understood by the current knowledge hence the high remedial costs in various projects. The proposed project is in collaboration with LUSAS, a UK-based leading developer of numerical tools. This new collaboration will add a critical weight via a new dimension to take the previous and ongoing research to high TRL levels.