Development of coupled centrifuge-numerical modelling to achieve a global tunnel-soil-structure interaction analysis

利用地下空间进行基础设施建设对现代城市的发展至关重要。英国伦敦Crossail项目的重大投资清楚地表明了这一点。隧道施工已经演变成一种复杂的施工过程，涉及到使用自动化设备和专业材料。然而，现代方法的使用并不能防止隧道施工造成的不可避免的地面变形。在现代城市中，由于地下基础设施的丰富，地下空间有限，了解隧道施工对附近地下基础设施和地上结构的影响是很重要的，分析隧道施工对地上结构的影响是一个极其复杂的土-结构相互作用问题。这个问题涉及隧道、土壤、地面结构的行为，以及土壤和结构组件之间发生的高度非线性相互作用。对个别领域(即孤立的土壤或结构)的分析可以提供一些关于整体行为的指示，但它不能真实地代表全球系统。现代设计和研究工具，如数值和土工离心机模型，能够准确地分别模拟土壤或结构域，但难以复制涉及土壤-结构相互作用的大型复杂系统的全球行为。该项目将开发一种方法，其中土工离心机和数值模拟技术以一种方式结合在一起，充分利用每种技术的各自优势，以获得隧道-建筑相互作用问题的准确的全局解决方案。该项目考虑了一个特定的场景，即在桩基础上的建筑下面建造一条隧道。利用诺丁汉大学土工离心机对隧道土桩基础进行了数值模拟。土工离心机允许在受控的实验室环境中测试全尺寸原型的小规模模型，并复制复杂的土壤和土壤-结构相互作用行为。离心机是必要的，以增加小比例模型中的土壤重量，使模型中的地应力和行为与全比例原型中的匹配；例如，当离心机旋转时，离心机模型中0.1米深的土壤部分与相同原型土的10米重相同，从而产生相当于模型中地球重力100倍的加速场。与数值模型相比，离心机模型能够更真实地模拟隧道开挖引起的位移及其引起的土-结构相互作用。对于隧道建设问题，使用数值模型来求解基础建造区域。考虑了这一领域的各种复杂性，如建筑-基础连接、建筑刚度和材料性能。该数值模型将提供对建筑物的准确模拟，这在比例离心机模型中是很难实现的。离心机和数值模型将通过数据接口系统耦合，该系统将在模型之间实时传递桩的位移和荷载信息。这种对接意味着捕捉到离心机中的物理模型和数值模型之间的相互作用，并正确地模拟了全球隧道-土壤-地基-建筑系统的行为。该项目的成功完成将代表着在改进建模方法以研究隧道-结构相互作用问题方面迈出的重要一步，并将提供有价值的信息，帮助提高对这一复杂而重要的施工场景的理解。

The use of underground space for infrastructure development is vital for the growth of modern cities. This is clearly demonstrated by the significant investment in the Crossrail project in London, UK. Tunnelling has evolved into a sophisticated construction process involving the use of automated equipment and specialist materials. The use of modern methods does not, however, prevent the unavoidable result of ground deformations caused by tunnelling. In modern cities, where underground space is limited due to the abundance of buried infrastructure, it is important to understand the effects of tunnelling on nearby buried infrastructure and above-ground structures.The analysis of the effect of tunnelling on above-ground structures is an extremely complex soil-structure interaction problem. The problem involves the behaviour of the tunnel, the soil, the above-ground structure, and the highly non-linear interactions that occur between the soil and structural components. Analysis of individual domains (i.e. the soil or structure in isolation) can provide some indication of overall behaviour but it does not give a true representation of the global system. Modern design and research tools, such as numerical and geotechnical centrifuge modelling, have the ability to accurately model the soil or structural domains individually but struggle to replicate the global behaviour of large complex systems involving soil-structure interactions.This project will develop a method in which geotechnical centrifuge and numerical modelling techniques are coupled together in such a way as to take full advantage of the respective strengths of each technique in order to obtain an accurate global solution to the tunnel-building interaction problem. The project considers a specific scenario in which a tunnel is constructed beneath a building on a piled foundation. The University of Nottingham geotechnical centrifuge is used to model the tunnel-soil-piled foundation domain. The geotechnical centrifuge allows testing of small-scale models of full-scale prototypes within a controlled laboratory environment and replicates complex soil and soil-structure interaction behaviour. The centrifuge is necessary to increase the weight of the soil in the small-scale model so that ground stresses and behaviour in the model match those in the full-scale prototype; for example a 0.1m deep section of soil in the centrifuge model weighs the same as 10m of the same prototype soil when the centrifuge is spun to give an acceleration field equivalent to 100 times earth's gravity in the model. The centrifuge model can provide a more realistic simulation of the tunnelling induced displacements and resulting soil-structure interactions than a numerical model.For the tunnel-building problem, a numerical model is used to solve the foundation-building domain. Various complexities of this domain are considered, such as the building-foundation connections, building stiffness, and material behaviour. The numerical model will provide an accurate simulation of a building which would be very difficult to achieve in a scaled centrifuge model.The centrifuge and numerical models will be coupled through a data interfacing system which will pass information of pile displacements and loads between the models in real-time. This interfacing means that the interactions between the physical model in the centrifuge and the numerical model are captured and that the global tunnel-soil-foundation-building system behaviour is modelled correctly.The successful completion of this project will represent a significant step in improving modelling methods to study the tunnel-structure interaction problem and will provide valuable information to help improve the understanding of this complex and important construction scenario.