Research on modeling of plough during cable laying operation

For burying cable ploughs need to follow a certain path, big ploughs are towed by surface vessels with powerful propulsion systems, modeling is rather important. Firstly, based on Colomb´s passive earth pressure theory, the analysis of effects of pore water, cavitation limit and grain crushing limit are carried out. Secondly, the mathematical model considering the force acting on the plough from the seabed-sediment was derived. It depended on the plough´s speed in surge, ocean depth, burial depth and width (shape of the plough share) and various seabed-sediment parameters. Finally, the simulation was implemented in Matlab, the results was reasonable and valid. To conclude, the research results are basically congruent with practice, but because Coulomb´s theory of passive earth pressure is little bigger. It can be found that as the ploughing speed increases or the deeper the burial, the greater the decrease in pore water pressure, and hence the greater the friction force and the mathematical model is nonlinear. So, when designing controller of cable laying vessel, the plough model can be used for a feed forward or a prediction. The different type of sediment has different parameter values. For simplicity in this assignment, only the density of the sediment is changed when simulating a change of sediment type.