Author: Dr.ir. S.A. Miedema The Cutting Forces in Saturated Sand of a Seagoing Cutter Suction Dredger

In dredging it is necessary to know about the conditions under which a dredging operation takes place. Important conditions to design a dredger or to determine the workability of a dredger (under offshore conditions) are the forces and the torque that appear on the excavating element. The paper describes the basic theory of the cutting of water-saturated sand and gives tables by which the cutting forces on a straight blade can be determined. With some assumptions the basic theory can be applied on a cutterhead and a dredging wheel. The equations found are simplified so that by means of tables given, the cutting forces and the torque can be determined. With this knowledge research has been carried out into the forces acting on a cutterhead submitted to simulated offshore conditions. It appeared that for these conditions, a model for a disc bottom cutterhead can be derived by combining the simplified cutterhead and dredging wheel theory. A strategy for the calculation of the cutting forces and the torque on a disc bottom cutterhead is given, whilst a result of the research carried out is shown. The theory given in this paper can be used to calculate the cutting forces and the cutting torque acting on a drag head, a cutterhead or a dredging wheel by means of a pocket calculator