鱼雷锚斜向贯入机理和抗拔承载特性研究

The depletion of shallow water hydrocarbon deposits has increasingly forced China to expedite its exploitation of deepwater resources in the South China Sea. As such, suitable mooring techniques are required to ensure the viability of these operations. Amongst a variety of offshore anchors is the newly developed torpedo anchor, whose advantages include rapid installation, low cost and good anchoring performance. Besides, its installation is much less constrained by water depth. These features make it ideal for anchoring various floating offshore platforms in areas with deep or ultra-deep water. The present research activities concerning the torpedo anchor are mainly focused on the penetration mechanism and pull-out capacity of the vertically installed torpedo anchor. Little is known about the performance of torpedo anchors that are installed at an inclination to the vertical. To address this knowledge gap, this project will examine the performance of inclined torpedo anchors by means of reduced-scale model tests, large deformation finite element analyses and theoretical analyses. Through a thorough and systematic research, this project aim to obtain an in-depth understanding of the failure mechanism of soil during the anchor penetration process and the failure mode of anchor while it is being pulled out. The project will evaluate the influence of various factors on the penetration depth and pull-out capacity, from which the key factor affecting the performance will be determined. The eventual objective of this project is to derive a systematic and rational approach for estimating the penetration depth and pull-out capacity of torpedo anchors that are installed at an inclination to the vertical. The applicant believes that this project will contribute significantly to the advancement of the design methodology of torpedo anchor. It is also expected to have a beneficial effect on the development of deep water anchoring technology in China, which will in turn provide technical assistance for the exploitation of deepwater resources in the South China Sea.

我国正加快南海深水油气资源开发步伐，海洋石油平台的深水锚泊技术是深水油气资源勘探开发所需关键技术之一。鱼雷锚是一种新型海洋深水锚基础。它具有安装简单快速、经济性好、锚泊性能佳、不易受水深限制等优势，非常适合用于各种浮式海洋石油平台的深水系泊。目前国内外针对竖向贯入鱼雷锚的研究正逐渐开展，而关于斜向贯入鱼雷锚的研究仍很匮乏。本项目针对斜向贯入鱼雷锚，采用小尺度物理模型试验、大变形有限元模拟和理论分析计算相结合的方法，开展贯入机理和抗拔承载特性的研究。通过系统研究揭示斜向贯入鱼雷锚贯入机理和失效模式；探寻斜向贯入鱼雷锚贯入深度和承载力的关键影响因素和影响规律；建立斜向贯入鱼雷锚贯入深度和承载力的科学计算方法。项目预期研究成果将有助于完善鱼雷锚设计计算方法，促进我国海洋深水锚泊技术进一步发展，为我国南海油气资源开发提供技术支持或技术储备。

鱼雷锚是一种新型海洋深水锚基础。它具有安装简单快速、经济性好、锚泊性能佳、不易受水深限制等优势，非常适合用于各种浮式海洋石油平台的深水系泊。本项目针对斜向贯入鱼雷锚的贯入和拉拔机理机制、贯入深度和拉拔承载力计算方法、鱼雷锚小比尺模型试验的试验误差、细颗粒海洋软土抗剪强度的率效应等多个相关科学问题开展了深入研究。研究手段包括物理模型试验、大变形有限元模拟、理论分析计算。研究结果表明斜向贯入鱼雷锚的贯入机理机制与竖向锚相似，贯入深度的关键影响因素包括锚初始贯入速度、土体强度和率效应参数、锚几何形状、锚重、锚土界面摩擦系数等；斜向鱼雷锚拉拔机理机制与竖向锚存在明显不同，关键影响因素包括拉拔平面夹角、平面内拉拔角、锚倾斜角、锚几何形状、锚土界面摩擦系数等。本研究项目针对斜向锚贯入深度和拉拔承载力提出了科学计算方法，为我国海洋深水锚泊技术发展和鱼雷锚设计优化提供了有益科学依据。同时，本项目还针对鱼雷锚小比尺模型试验存在的试验误差开展了深入分析，阐明了误差产生的原因、量化了误差的大小、提出了控制误差的有效手段。此外，针对鱼雷锚贯入过程中细颗粒海洋软土抗剪强度的率效应问题，也开展了深入探讨，提出了一种具有率效应扩展的修正剑桥模型。截止项目结题日期，依托本项目已发表和待刊SCI论文数目已达6篇，大幅超过了原定目标。