往复荷载作用下群锚系泊系统的承载力演化和失稳机理研究

Offshore floating structures are secured to the seabed via mooring systems, which normally consist of multiple anchors. The cyclic loading caused by typhoons frequently leads to an initial failure at the weakest anchor and consequently results in the collapse of the whole mooring systems. This project aims to study the holding capacity evolution and failure mechanism of mooring systems with multiple anchors. Employing laboratory model tests, numerical modelling and theoretical derivations, this project expects to explore these three aspects: (1) the soil strength change and anchor holding capacity development under cyclic loading; (2) the loading sharing mechanism and geotechnical behaviour of the remained anchors after partial failure; (3) stability improvement design under extreme loading condition. Based on advancing the understanding of the failure mechanism of mooring systems, this project’s expected outcome will include: proposing a new calculation method for anchor holding capacity under cyclic loading; establishing a numerical model to predict the trajectory of mooring systems with six degree of freedom; stability improvement solution for mooring systems in order to enhance the security under extreme loading conditions.

漂浮式海洋结构设施通过多组锚组成的群锚系统系泊在海床上，台风引起的往复荷载常造成部分锚组破坏，进而引起整个群锚系泊系统的失稳和崩溃。本项目旨在探究往复荷载作用下群锚系泊系统的承载力演化规律和失稳机理，项目通过模型实验、数值模拟和理论推导手段，从三个方面进行解答：(1)往复荷载作用下的土体强度变化和锚承载力演化规律；(2)部分锚组破坏后，剩余锚泊系统的荷载分配机制和力学响应；(3)极端荷载条件下，群锚系统稳定性提升方案研究。在深入研究群锚系统承载力演化和失稳机理这一科学问题的基础上，本项目预期的研究成果包括：提出往复荷载作用下锚的承载力的计算方法；建立预测群锚系统在空间六自由度荷载作用下运动的计算模型；提出群锚系统稳定性提升方案，提高锚泊系统在的安全性和可靠性。

随着海洋油气开发走进深水，以及海洋可再生能源的兴起，漂浮式结构正在取代传统的固定式结构，成为深水海域能源开发的主要技术手段。漂浮式结构通常由多组锚和锚链组成的“群锚”系统系泊在海床上，在台风下容易造成部分锚组破坏，从而导致群锚系统失稳。本项目进行了模型实验、数值模拟和理论推导，研究成果如下：(1) 获得了往复荷载作用下土体强度变化和锚承载力演化规律，提出往复荷载作用下锚的承载力计算方法，建立预测锚在空间六自由度荷载作用下运动的计算模型；(2) 明确了部分锚组破坏后，剩余锚泊系统的荷载分配机制和力学响应； (3) 提出锚泊系统稳定性提升方案，提高锚泊系统的安全性和可靠性。