Removal of a dumped rock cover with a low pressure jet

Pipelines and cables on the sea bottom are usually protected by a cover of dumped rock. In case of maintenance or removal works, this cover has to be removed in order to expose the pipeline. This removal can be performed by means of a mass flow excavation process, created with a submerged jet flow. However, the exact erosion processes of a...

Post-trenching with a trailing suction hopper dredger

It is common practice to protect subsea pipelines by embedding them into the soil. Trenches can be made before or after the pipelines have been laid. In the latter case, the excavation process is called post-trenching. The essence of post-trenching, as handled in this thesis, is erosion of sand by a water-jet. The literature study focused on the...