ALPACA: Axial-Lateral Pile Analysis for Chalk Applying multi-scale field and laboratory testing

白垩是一种高度可变的软岩，覆盖了北欧的大部分地区，并广泛分布于北海和波罗的海。这给港口、桥梁和海上风力涡轮机结构的大型基础设计人员带来了重大问题，这些结构必须在数十年的服务中承受严重的环境载荷。在使用大型打孔钢桩来固定结构时，面临着特殊的困难。虽然打入桩基础解决方案有许多潜在的优势，但粉笔对打桩和服务荷载条件高度敏感，例如在风暴和海浪影响下，桥梁，港口和海上结构所应用的反复循环抖振。目前关于如何考虑困难的打桩条件或预测桩对荷载的垂直和横向响应的指导是出了名的不可靠。目前也没有关于（行驶后）时间对桩行为的潜在积极影响或结构及其桩基础不可避免地经历的循环荷载的一般负面影响的工业指导。这些知识的不足给英国和北欧的一系列项目的评估和设计带来了很大的不确定性。特别受影响的是一系列计划中的和现有的大型海上风力发电场的发展。基础设计和性能的不确定性对重要的可再生、低碳、海上能源供应的经济和安全利用构成了威胁。更好的设计指导方针将降低海上风能成本，也有助于港口和运输项目的进展和有效运作，从而为个人消费者和英国工业带来额外的好处。拟议的研究将通过一个全面的高质量现场试验方案，为白垩场地提供新的打孔桩设计指导，包括多种加载情景，在肯特郡的一个陆上试验场对21个专门仪器化的打孔钢管试验桩进行试验。这将形成一套基准结果，并将辅以全面的先进钻探、取样、原位测试和实验室实验，并辅以对其他病例历史数据的严格分析和密切分析。关键目标是开发设计程序，以克服目前在打桩、老化、轴向和横向荷载下的静态和循环响应方面的知识不足。主要成果将是适用于陆上和海上应用的实用设计指南。

Chalk is a highly variable soft rock that covers much of Northern Europe and is widespread under the North and Baltic Seas. It poses significant problems for the designers of large foundations for port, bridge and offshore wind turbine structures that have to sustain severe environmental loading over their many decades in service. Particular difficulties are faced when employing large driven steel piles to secure the structures in place. While driven pile foundation solutions have many potential advantages, chalk is highly sensitive to pile driving and to service loading conditions, such as the repeated cyclic buffeting applied to bridge, harbour and offshore structures by storm winds and wave impacts. Current guidance regarding how to allow for difficult pile driving conditions or predict the piles' vertical and lateral response to loads is notoriously unreliable in chalk. There is also no current industrial guidance regarding the potentially positive effects of time (after driving) on pile behaviour or the generally negative impact of the cyclic loading that the structures and their piled foundations will inevitably experience. These shortfalls in knowledge are introducing great uncertainty into the assessment and design of a range of projects around the UK and Northern Europe. Particularly affected are a series of planned and existing major offshore wind farm developments. The uncertainty regarding foundation design and performance poses a threat to the economic and safe harnessing of vital renewable, low carbon, offshore energy supplies. Better design guidelines will reduce offshore wind energy costs and also help harbour and transport projects to progress and function effectively, so delivering additional benefits to both individual consumers and UK Industry.The research proposed will generate new driven pile design guidance for chalk sites through a comprehensive programme of high quality field tests, involving multiple loading scenarios, on 21 specially instrumented driven tubular steel test piles, at an onshore test site in Kent. This will form a benchmark set of results that will be complemented by comprehensive advanced drilling, sampling, in-situ testing and laboratory experiments, supported by rigorous analysis and close analysis of other case history data. The key aim is to develop design procedures that overcome, for chalk, the current shortfalls in knowledge regarding pile driving, ageing, static and cyclic response under axial and lateral loading. The main deliverable will be new guidelines for practical design that will be suitable for both onshore and offshore applications.