Backfilling head
After trenching and direct sidecasting with the trenching head, a ridge of situ soil has been formed close to the trench. This soil needs to be used as backfilling material after cable lay.
For this purpose, a backfilling head was designed that would directly sidecast the soil of the ridge into the trench. This way, backfilling would be a one-step operation reducing execution time and losses of fines.
This was achieved by designing a backfilling visor that fits the fixed part of the trenching head. The soil in the ridge next to the trench is scooped by the visor and blown sideways into the trench by using the reverse mode of the dredging pump.
Design
The backfilling visor had to make it possible to remove the ridge of sidecasted soil and blow it into the trench, without digging into the original seabed level. Key elements in the design to reach this goal are:
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correct design of the visor to scoop the rigde and guide the backflow of the pump in a horizontal direction towards the trench
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design of visor and teeth to only scoop the ridge and not to dig into the original seabed