Study on the feasibility of using an active draghead for rock dredging
Type:
Presented during:
WODCON XVII: "Dredging in a Sensitive Environment" - 2004, Hamburg, Germany
Authors:
ir. S.F.Sloot, Prof. ir. W.J. Vlasblom, and ir. V.C. van Gool
Abstract: The underwater excavation of rock is usually performed by CSDs (cutter suction dredgers). However the use of CSDs, is greatly restricted by the influence of waves, which in many cases prevent the use of a CSD in the open sea. This is certainly a reason to consider the possibility of using a TSHD (trailing suction hopper dredger) to dredging rock. This is a type of dredger that has demonstrated its capability to dredge sand and clay in the open sea. This paper deals with the feasibility of using an active draghead for soft rock dredging by TSHDs.
There are many different methods for the excavation of rock but few are suitable to be used in a draghead. Most methods can be excluded because of the boundary conditions under which the draghead has to operate, like: available thrust force of the TSHD, trailing speed, the unsteady motion of the draghead caused by wave-induced movement of the ship and the available space on board. Three promising methods are investigated and compared to illustrate their performance under various conditions.
Keywords: active draghead, rock dredging, excavation, TSHD, CSD