深海复杂环境下宽浅型筒型基础整机沉放姿态控制方法及机理研究

The bucket foundation is a highly efficient, low cost and environment-friendly infrastructure which can be widely used in the large-scale development of offshore wind power. The whole-machine transportation and one-step installation technology have achieved good demonstration effect in the shallow waters of Jiangsu Province (< 15m). In order to further extend this original technology to deeper seas, it is necessary to conduct in-depth research on the instable problem of the whole machine in the complex environment of deep water. To effectively achieve the state control of the bucket foundation during the self-weight sinking process and avoid the risk of overturning resulted from sea loads on the foundation, it is a challenging issue in terms of the engineering application. This project focuses on improving the safety and stability of deep water sinking operation of the bucket foundation and establishing the simulation and response model of the installation vessel-gauge pile-auxiliary cable system with the consideration of deep sea environment loads. The aim is to propose and verify the cable-assisted control method and mechanism of the phased sinking process of the composite bucket foundation. In addition, the calculation method of ultimate load will be studied to expand the scope of application of composite bucket foundation in different water depths of offshore wind farms.

筒型基础是一种在海上风电规模化开发上大有可为的高效、低成本、环境友好型基础结构，与其配套的整机运输及一步式安装技术已在江苏较浅海域（<15m）取得了良好的示范效应，为了将此原创技术进一步推广至较深海域，需要对深水复杂环境下整机安装所面临的失稳问题展开深入的研究。如何有效地实现基础入泥前自重沉放阶段的姿态控制，避免风浪流荷载对基础深水沉放过程所带来的失稳风险，满足整机沉放作业过程中发电机组对稳性的高标准要求，势必是宽浅型筒型基础工程应用层面所亟待解决的核心理论问题。本项目以提高筒型基础整机深水沉放安全性和平稳性为核心，建立安装船-定位桩-辅助拉索-筒型基础-整机在深水风浪流环境中沉放的安全性态演化及响应模型，提出并验证拉索辅筒型基础整机分阶段沉放（快速下沉阶段、悬停稳定阶段、无扰动入泥阶段）姿态控制技术及深水沉放施工极限环境荷载计算方法，为宽浅型筒型基础在不同水深海域风电场的应用奠定基础。

本项目以筒型基础从“近浅海”到较“深远海”风电场推广应用过程中所面临的复杂海洋环境下基础与机组整机沉放失稳问题为研究导向，通过深入的理论分析、数值模拟、模型试验、现场监测及检验等方式，重点开展了深海复杂环境下筒型基础整体沉放失稳模式及机理研究、拉索辅助宽浅型筒型基础整机水中沉放姿态控制技术研究、筒型基础土中沉放及精细化调平控制技术研究。提出了能够在深海复杂环境下实现筒型基础整体安全沉放的技术，也即“拉索辅筒型基础整机水中分阶段沉放姿态控制技术及土中精细化调平控制技术”。基于实际工程中宽浅型单筒多舱基础、宽浅型三筒及四筒导管架基础原型样机，开展了多种比尺的室内模型试验，并通过我国江苏及福建等多个海上风电场的实际实施，验证了此项技术的可行性及理论方法的准确性。最终，在申请人课题组团队及多家单位的共同努力下，成功地将筒型基础在我国的适用及安全沉放水深从2017-2018年的12m-15m（江苏响水及大丰海上风电场）扩展到了2020-2022年的16m-45m（福建、江苏、广东等海上风电场），并在实践过程中对沉放控制理论与方法进行了检验及优化。综上，本项目重点解决了筒型基础在较“深远”海域整机“水中+土中安全沉放”的技术难题，并实现了整机“安装过程”的技术降本，进一步扩大了宽浅型筒型基础及一步式安装技术在不同水深海域风电场的应用范围。