海洋串联锚嵌入机理及承载力分析方法研究

The exploration of marine sources provides the solution for the energy supply and demand contradictions. The tandem system anchors are composed with at least two drag embedment anchors. The application of tandem system anchors as foundation for offshore structure in ultra-deep water can significantly save construction cost and provide sufficient capacity against the extreme loading condition. The restraining-compensation interaction mechanism between the leading anchor and the piggy-back anchor in the tandem system is the key scientific problem during the drag embedment process..With the magnetic tracking devices developed by the applicant, this project will first focus on pure normal, pure shear, pure rotational pitch loading tests to explore the bearing capacity factors for a single drag embedment anchor. These measured capacity factors are for characterizing plastic yield surface from the interaction drag anchors with soft soil. Next, the centrifuge drag tests with tandem system anchors will be performed with the variation of initial embedment depth, initial pitch angle, spacing between the piggy-back anchor and leading anchor, the attachment point of piggy-back to the leading anchor. These results will facilitate a better understanding of the interaction mechanism between the leading anchor and the piggy-back anchor. The trajectory and orientation prediction model for the tandem system anchors will be proposed. The pull-out capacity under normal loading, in-plane shearing, and out-of-plane loading will be simulated by CEL method. This research will enrich the types of offshore foundation, and provide solid scientific basis and technical support for the design and application of the tandem system anchor on offshore oil and gas platforms.

开发海洋资源是解决我国能源供需矛盾的重要途径。海洋串联锚是一种将两个或以上的传统拖曳锚组合而成的新型混合锚，它具有易安装、用料省、锚固效率高等优点，更适用于抵抗深海复杂荷载。其在嵌入过程中前锋锚与背驮锚之间的相互牵制-补偿耦合作用机制是需解决的关键科学问题。.本项目基于申请人研发的磁感应定位和测向技术，开展全切向、全法向、全纵摇和切向-法向-纵摇转矩三向耦合荷载作用下单一锚体的嵌入离心模型试验，提出能反应锚体嵌入过程中海洋软土局部破坏的锚体塑性屈服面模型；在此基础上，针对不同初始嵌入角度及深度、串联锚内部的锚固方式，通过开展串联锚拖曳离心模型试验，获得其嵌入轨迹及姿态，揭示前锋锚与背驮锚耦合作用机理，并提出相应的轨迹分析模型和承载力分析方法，为其设计和应用提供重要的科学依据和技术支撑。

开发海洋资源是解决我国能源供需矛盾的重要途径。深海串联锚是一种将两个或以上的传统拖曳锚组合而成的新型混合锚，它具有易安装、用料省、锚固效率高等优点，更适用于抵抗深海复杂荷载。其在贯入过程中前锋锚与背驮锚之间的相互牵制-补偿耦合作用机制是需解决的关键科学问题。.为阐明串联锚安装过程贯入过程中系统内部相互耦合机制，本研究首先从单一锚体与土体相互作用下的运动特性出发，利用定位测向磁感应追踪技术，开展三向耦合荷载下的拖曳贯入常重力和超重力离心模型试验，进而提出新型串联锚的贯入轨迹分析模型及承载力分析方法。探索锚板运动方向、锚板-锚胫夹角、锚眼处拖曳力和拖曳角以及泥面处夹角等参数对贯入轨迹的影响。具体工作如下：.(1) 探究了六自由度磁感应定位系统的原理以及在超重力下岩土工程模型试验中的有效性，解决了超重力模型试验中基础在地基中的运动轨迹参数因土体不可透视而难以直接测量的难题。.(2) 开展了拖曳锚单锚和串联锚安装常重力缩尺模型，探究了锚胫角、初始埋深等因素对于单锚贯入性能和承载力的影响，以及初始埋深、两锚间距等因素对于串联锚贯入性能和承载力的影响，发现串联锚承载力通常大于两倍单锚承载力，其一加一大于二的承载力叠加效应是由串联锚中的前锋锚嵌入机制由切向破坏变为转动破坏机制。.(3) 开展了拖曳锚单锚和串联锚拖曳安装超重力模型试验，探究了初始埋深、两锚间距和锚体大小等因素对串联锚贯入性能和承载力的影响。.(4) 建立了考虑三向荷载作用下单一锚体的塑性屈服面，利用了全切向轨迹贯入、全法向轨迹贯入、全纵摇转矩贯入、切向-法向-纵摇转矩三向荷载作用下单一锚体贯入的模型试验结果以及磁感应定位测向追踪技术监测的三向荷载作用下单一锚的贯入过程，验证了所提出的塑性屈服面模型。