Seabed structures and foundations related to deep-sea resource development:A review based on design and research

The deep‐sea ground contains a huge amount of energy and mineral resources,for example,oil,gas,and minerals.Various infrastructures such as floating structures,seabed structures,and foundations have been developed to exploit these resources.The seabed structures and foundations can be mainly classified into three types:subsea production structures,offshore pipelines,and anchors.This study reviewed the development,installation,and operation of these infrastructures,including their structures,design,installation,marine environment loads,and applications.On this basis,the research gaps and further research directions were explored through this literature review.First,different floating structures were briefly analyzed and reviewed to introduce the design requirements of the seabed structures and foundations.Second,the subsea production structures,including subsea manifolds and their foundations,were reviewed and discussed.Third,the basic characteristics and design methods of deep‐sea pipelines,including subsea pipelines and risers,were analyzed and reviewed.Finally,the installation and bearing capacity of deep‐sea subsea anchors and seabed trench influence on the anchor were reviewed.Through the review,it was found that marine environment conditions are the key inputs for any offshore structure design.The fabrication,installation,and operation of infrastructures should carefully consider the marine loads and geological conditions.Different structures have their own mechanical problems.The fatigue and stability of pipelines mainly depend on the soil‐structure interaction.Anchor selection should consider soil types and possible trench formation.These focuses and research gaps can provide a helpful guide on further research,installation,and operation of deep‐sea structures and foundations.

锚泊线海床开槽与锚泊基础承载力研究进展综述

Mooring systems are usually adopted to position floating structures,including mooring lines and anchors,and directly determine the safety of floating structures.Seabed inspection reported that seabed trenches induced by mooring line-soil interaction appear in front of the anchor and reduce the anchor bearing capacity.This work first introduces the research progress of mooring line-soil interaction and seabed trenching simulation.Research about the suction anchor capacity in clay and sand is presented,and the seabed trench influence on anchor capacity is analyzed.For anchor analysis,this study gives a new perspective to analyze anchor installation and bearing capacity,i.e.,structure-soil interface characteristic.Some common anchor types are analyzed.Results showed that seabed trench simulation is still needed to acquire trench 3D profiles,in which the mooring line-soil dynamic interaction cannot be ignored.At present,the trench influence is not considered in suction anchor design,making the design dangerous.For the anchor,the interface shear characteristics control the most unfavorable loading conditions.Thus,accurate interface parameters should be obtained for anchor analysis.

Shared mooring systems for offshore floating wind farms: A review

Offshore wind energy,as a form of renewable power,has seen rapid development in recent years.While fixedbottom wind turbines are typically used in water depths less than 50 m,the utilization of floating offshore wind turbines(FOWTs)becomes essential for deeper waters.Secure and effective mooring systems play a crucial role in making FOWTs commercially viable.The concept of a shared mooring system offers an innovative solution for deploying floating wind farms in clusters or arrays,which can reduce overall construction costs for large-scale floating wind farms.It is imperative to optimize the shared mooring arrangement for maximum cost-effectiveness and wind farm stability.However,implementing a shared mooring system introduces complexity to the dynamics of FOWTs,requiring the development of advanced simulation tools to meet modelling requirements.Under the shared mooring arrangement,mooring lines and anchors face more significant challenges,such as chain-seabed interactions,soil cyclic weakening,and anchor out-of-plane loading,which underscore the need for innovative,reliable,and efficient shared anchor designs.This article offers an overview of the current research status on shared mooring systems for floating wind farms,which might serve as a valuable reference for the construction of large-scale floating wind farms worldwide.