Mechanics and control of submarine cable laying.

摘要

Submarine cable systems are a vital and expanding part of the world wide telecommunication network. The systems are laid in the ocean using a cable ship. During the deployment of a submarine cable, the cable ship has only limited information about the behaviour of the cable once it leaves the vessel and begins its descent to the seabed. The present thesis studies the cable dynamics and control during laying operations.; The cable dynamics is modeled using the continuum approach. Using the model developed, the cable configuration and tension are obtained for the two dimensional steady state and transient motions, when different parameters such as the ship velocity, hydrodynamic constant, and current direction, are varied. Also, the out of plane angle of inclination and corresponding maximum displacement for the three dimensional steady state case are determined.; Then the possibility of controlling the cable oscillations by varying the payout rate is explored. In the case of the controlled response the results show that, in principle, the deviation of the in plane angle can be effectively reduced to zero, but the value of the input payout rate needed is unrealistic in practice.