Abstract: Because of better performances both in pullout capacity and deepwater installation, drag anchors are increasingly applied and play a key role in deepwater mooring systems. During the anchor installation, complicated interaction happens between the anchor and installation line. The penetration and motion of drag anchors are directly affected by the reverse catenary shape of the embedded installation line. Investigating the reverse catenary shape is important for improving the drag embedment performance, precisely predicting the anchor trajectory, and solving the positioning problem of the anchor. In the present work, the reverse catenary equations which can be used to simulate the reverse catenary shape of the embedded installation line both for cohesive and noncohesive soils are derived based on the mechanical model for the embedded line. A technique for real-time measuring the reverse catenary shape based on the tilt transducers and the circular recursive algorithm is also developed. Three typical line profiles are selected to verify the rationality of the experimental technique in the air. The results show high accuracy between the real line profiles and the measured curves by using the technique. The accuracy of the developed equations for simulating the reverse catenary shape of the embedded line is verified by model experiments using the real-time measurement technique. Besides, the model experiments help us to understand the variation of the reverse catenary shape of the embedded anchor line during installation.

Key words: drag anchor, installation line, reverse catenary shape, model experiment