The Unified Analytical Model And Applications Of Complicated Mechanical Properties And Kinematic Behaviors Of Deepwater Anchors

As the key element of deepwater mooring systems,the good performance of deepwater anchors is the key to guarantee the safety and stability of mooring systems.In the system of anchor-soil-line,different types of deepwater anchors will present complicated mechanical properties and kinematic behaviors.The key to study the properties of deepwater anchors is to rationally analyze the kinematic state of anchors in the seabed,and the performances of different kinematic states are closely related to the mechanism.Through exploring and revealing the mechanism,the complicated anchor properties can be understood and analyzed fundamentally,and then the unified analytical model can be developed as the efficient theoretical tool for the complicated analysis and application of anchors.Based on the engineering practice of deepwater anchors,different types of deepwater anchors(anchor pile,suction anchor,drag anchor and gravity-installed anchor)are studied,and several key problems in the application and analysis of these anchors are explored and solved through establishing the unified analytical model for complicated mechanical properties and kinematic behaviors of deepwater anchors in the seabed.For deepwater anchors,with the unified description of the forces,the kinematic behaviors,the mechanism and the analytical principle of anchors,and through dividing the comprehensive anchor behaviors into diving,pulling out and keying,and then combining with the correponding mechanical model and the least-force principle,the unified analytical model suitable for different anchors in cohesive and cohesionless soils is developed,and the complicated mechanical properties(failure mode,pullout capacity)and kinematic behaviors(diving,keying,pulling out,trajectory)of anchors can be analyzed and determined.The unified analytical model is of great significance.With the developed model,the complicated properties of deepwater anchors can be analyzed and understood fundamentally,the key problems on the anchor properties can be solved conveniently and efficiently,and the analytical applicability of the anchor properties is also improved.For anchor piles(suction anchors),the failure mode and pullout capacity of anchors in the seabed are deeply studied with the unified analytical model,and an efficient analytical method for the optimal position of the attachment point of anchors is proposed.The results demonstrate that,the failure mode includes three types,i.e.,the horizontal failure,the vertical failure and the inclined failure.A bump exists in the relation curve between the horizontal and vertical pullout capacities of anchors.The mooring angle has a monotonic relationship with the ultimate pullout capacity of anchors.For drag anchors in the seabed(layered soils),the comprehensive anchor behaviors are deeply studied and the complicated anchor trajectories are deeply analyzed with the unified analytical model.For gravity-installed anchors(OMNI-Max),the comprehensive anchor behaviors and the anchor trajectories in the seabed are deeply studied with the unified analytical model.The analytical model for the profile and tension transmitting properties of the anchor line embedded in layered soils is established.The results demonstrate that,comparing to the cohesive layer,the curvature of the line is bigger and the tension loss is more severe in the cohesionless layer.With increasing depth of the line,the tension in the line decreases.The tension angle at the shackle will increase with increasing normal soil resistance.