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应用从根本上改变了微型混凝土的设计。由于对强化学物质的依赖，新混凝土的性能和行为对其成分、搅拌和工艺都很敏感，导致深基坑施工中的各种故障，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，本项目旨在通过开发新的数值工具来研究新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，这些工具有助于理解全尺寸深基础施工背景下微型混凝土的多相物理。该项目将系统地调查混凝土特性、基础设计、施工过程和完工质量之间的关系，其中特别关注加固设计的影响、混凝土混合物的可变性以及支撑流体的特性和现场条件。深基坑施工过程涉及土、支护流体和微孔混凝土三种材料体系，每一种材料都是多相材料，具有各自的形态。复杂的多物理场相互作用同时存在：流体失入土体形成、土体颗粒冲刷出、土体、水泥浆与支护流体混合形成界面层、混凝土拌合物渗水、粗集料离析、墙体滤饼形成等。这些都影响了深基坑的竣工质量，而现有的知识对这些问题的认识还不够充分，因此在各种工程中造成了很高的补救费用。拟议的项目是与LUSAS合作的，LUSAS是一家总部位于英国的领先的数值工具开发商。这项新的合作将通过一个新的维度增加一个关键的权重，使以前和正在进行的研究达到更高的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.