Designing a laboratory model test program for developing a new offshore anchor
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The Flying Wing Anchor (patent pending) is a new anchor concept that combines the features of dynamically penetrating anchors, drag embedment anchors, and plate anchors. To study and optimize the behavior of the new anchor, this study developed a simplified predictive model and a new data acquisition system for performing physical model tests. The simplified predictive model couples a limit-equilibrium-based model for the anchor line and a plasticity-based model for the anchor to predict the embedment trajectory and holding capacity of the new anchor. The new data acquisition system is used to record data from sensors and control the movement of an electric motor. The system was developed by LabVIEW and demonstrated with a model test. The following major conclusions are drawn from this work about the behavior of this anchor concept in clay: (1) The pitch angle at the initiation of dive can be optimized to achieve the maximum dive depth and ultimate holding capacity. (2) The maximum depth of the dive is not strongly dependent on the undrained shear strength of the soil, while the ultimate holding capacity is proportional to the undrained shear strength of the soil at the maximum dive depth. (3) A smaller diameter of the line makes the anchor dive deeper and increases the ultimate capacity. (4) A deeper initial embedment depth after free fall makes the anchor dive deeper and increases the ultimate capacity. (5) A series of model tests to calibrate the simplified predictive model for the performance of the anchor should consist of varying the thickness of the line, the depth of initial embedment, the pitch angle at the initiation of dive, and the profile of undrained shear strength versus depth. It is recommended that model tests be conducted using the guidance presented in this thesis.