Theoretical Study On The Three-dimensional Profile And Tension Transmitting Properties Of Mooring/Installation Lines In Marine Clay

As key components of the mooring system,anchor lines connect the anchors and the floating moored platform.On the one hand,the movement of the anchor handling vessel or the floating moored platform leads to the complex motion of the anchor in the seabed by the drag of installation or mooring line;on the other hand,with the soil resistances,the embedded anchor line will present a special deformation.When the floating structure suffers extreme environmental loadings,the mooring system may partially fail,such as breaking of one or more anchor lines within the spread.In such a scenario,the orientation of the intact lines may change dramatically and the anchor may even present a three-dimensional motion in the seabed,attributed to the long-distance drift of the floater.Hence,both the anchor and the anchor line will experience out of plane loadings.To evaluate the anchor capacity and the anchor behavior under out of plane loading,the three-dimensional behavior of embedded anchor lines should be fully understood in advance.In the present work,a theoretical method is developed to analyze the three-dimensional behavior of embedded anchor lines,including the three-dimensional profile and tension transmitting properties of the line both in clay and in sand.And the effects of adhesion factor?_l on the reverse catenary properties and three-dimensional behaviors of embedded anchor lines in clay are considered.According to the established theoretical model,a corresponding numerical solution flow is put forward.The established solution flow can not only analyze the three-dimensional profile and tension transmitting properties of embedded anchor lines during the working state of anchor,but also analyze that even when the anchor presents a complex motion in the seabed.A systematic comparative study is performed with the existing research work to examine the efficiency of the proposed method.Then,two examples of application are designed to analyze the three-dimensional profile and tension transmitting properties of embedded anchor lines under out of plane loading.In the first application example,the attachment point of the embedded anchor line is fixed and the touchdown point of the embedded anchor line changes under a given displacement condition.The first application example corresponds to the partial failure of mooring systems,where an offset of the platform occurs with the anchor fixed at the original penetration.In the second application example,both the anchor line and the anchor present motion in the seabed.The second application example corresponds to an engineering case,where the anchor is motivated by the drifting platform and dives a long distance in the seabed during an ultimate test of OMNI-Max anchor.The two examples correspond to the two typical states of the mooring systems under the ocean environment loadings.Through systematic analyses and examinations,the understanding of the deformation and the tension transmitting properties of the embedded lines in the seabed is sharped,which aims to provide a useful reference for the engineering application.