Development of smart integral bridges

智能整体桥梁的发展

• 批准号: 2439660
• 金额: --
• 依托单位: University of Cambridge
• 依托单位国家: 英国
• 项目类别: Studentship
• 财政年份: 2020
• 资助国家: 英国
• 起止时间: 2020 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=studentship-2439660
• 关键词: Development; smart; integral; bridges

The use of integral bridges with a combined bridge deck and abutment walls has been in use for many decades. However their current design is largely based on PD6694 guidelines, which involves a significant amount of empiricism and uncertainty. This is largely due to the unknown stress state and the stress-strain behaviour of the backfill soil behind the abutment walls. The designs can get more conservative with an increase in the span of the bridges. It is also worth noting that older bridges that have bearings can cease up and act like an integral bridge during later years of their service, applying similar loads on the abutment walls and the soil backfill behind these. There is a well-recognised need to reduce the carbon footprint of bridges while delivering a sustainable and resilient highway infrastructure that is robust under climate change. This proposal is aimed at investigating the integral bridge and abutment design with the ultimate aim of improving the design, reduce maintenance and increase the inspection intervals with suitable deployment of smart instrumentation during the construction of these bridges. With this view, the research proposal is divided into three interdependent phases.Phase I: Deployment of smart instrumentation during bridge construction: In this phase the stakeholders such as the bridge owners, designers, contractors, Highways England, the academics and the research staff are brought together to design the deployment of smart instrumentation that can help with monitoring of thermal expansion of decks, bending moments and shear forces on the deck-abutment wall joints, earth pressures behind the abutment wall, strains mobilised in the backfill soil etc. The selected bridges with this smart instrumentation will be monitored over a long period of 5 to 10 years and will involve many thermal cycles.Phase II: Development of physical and numerical modelling: Simplified physical models of the integral bridges and the backfill that are highly instrumented will be developed and tested in the large 10m diameter beam centrifuge at Cambridge. Soil strains in the backfill will be recorded directly using highresolution imaging and use of the geo-PIV software. It is planned that about 5 to 6 centrifuge models will be tested varying the backfill soils, use of geo-foam blocks behind the abutment wall etc. The cost of the centrifuge testing is estimated at about £6k per test. The centrifuge data will be compared to field data, flowing from Phase I of the project at appropriate intervals. In addition, numerical modelling using the finite element method will be carried out and these models will be calibrated against the centrifuge test data. Also the results from the calibrated FE analyses will be compared to field monitoring data flowing from Phase I.Phase III: Development of design guidelines: In this phase the validity of the current design guidelines is verified. With the view of minimising the carbon footprint and producing a resilient bridge structure that can cope with climate change concerns, the guidelines will be updated for use in future integral bridge design. It is also anticipated that use of more carefully chosen backfill materials with use of geofoams or geo-grids, the designs can be further optimised to minimise the abutment wall movement inducing large strains in the backfill. The possibility of using an optimal thickness of these geo-synthetic material sections to reduce soil strains and any subsequent soil deformation will be investigated.

具有组合桥面和桥台墙的整体桥梁的使用已经使用了几十年。然而，他们目前的设计主要是基于PD 6694指南，这涉及到大量的不确定性和不确定性。这在很大程度上是由于未知的应力状态和应力应变行为的回填土背后的桥台墙。随着桥梁跨度的增加，设计可能会变得更加保守。同样值得注意的是，有支座的旧桥在其服役的后期可能会停止使用，并像一座完整的桥梁一样，在桥台墙上施加类似的荷载，并在桥台墙后面回填土。减少桥梁的碳足迹，同时提供可持续和有弹性的公路基础设施，在气候变化下保持稳健，这是一个公认的需求。本提案旨在调查桥梁和桥台的整体设计，最终目的是改进设计，减少维护，并在这些桥梁的施工过程中适当部署智能仪器来增加检查间隔。基于这一观点，研究方案分为三个相互依赖的阶段。第一阶段：桥梁施工期间智能仪表的部署：在这一阶段，桥梁业主、设计师、承包商、英格兰高速公路、学者和研究人员等利益相关者将聚集在一起，设计智能仪器的部署，以帮助监测桥面的热膨胀，桥面-桥台墙接缝上的弯矩和剪力、桥台墙后的土压力、回填土中的应变等。将对使用该智能仪器的选定桥梁进行5至10年的长期监测，并将涉及许多热循环。第二阶段：物理和数值建模的开发：将在剑桥的大型10米直径梁式离心机中开发和测试高度仪器化的整体桥梁和回填的简化物理模型。回填土中的土壤应变将使用高分辨率成像和geo-PIV软件直接记录。根据计划，将对约5至6个离心机模型进行试验，以改变回填土、桥台墙后土工泡沫块的使用等。离心机试验的成本估计为每次试验约6000英镑。将在适当的时间间隔内将离心机数据与项目第一阶段产生的实地数据进行比较。此外，将使用有限元法进行数值建模，并将根据离心试验数据对这些模型进行校准。此外，校准FE分析的结果将与第一阶段的现场监测数据进行比较。第三阶段：设计指南的制定：在此阶段，验证当前设计指南的有效性。为了最大限度地减少碳足迹，并生产出能够科普气候变化问题的弹性桥梁结构，该指南将进行更新，以用于未来的整体桥梁设计。还可以预期，使用更仔细选择的回填材料以及土工泡沫或土工格栅，可以进一步优化设计，以最大限度地减少在回填中引起大应变的桥台墙移动。将研究使用这些土工合成材料部分的最佳厚度以减少土壤应变和任何随后的土壤变形的可能性。