Comparison of Experimental and Theoretical Forces on a Model Dredge Cutterhead

Dredging is a critical part of maintaining the nation?s ports and harbors that play a major role in international trade. The design of dredge equipment requires knowledge of the forces expected on an average dredge. For a cutter suction dredge one of the largest forces is applied on the cutter head. To determine the design criteria for a given cutter suction dredge the forces on the cutter head must be known. Forces on a 33 cm (13 inch) model cutter head have been measured using a model cutter suction dredge 10.2 cm ( (4 inch)) suction and 3 inch (7.6 cm) discharge) in the Haynes Coastal Engineering Laboratory. The experimental results are compared to the results of a previously developed theory for estimating cutterhead forces. A MATLAB program is written and used to solve the theoretical equations. The sediment used in the study had a d50 of 0.27 mm and an angle of internal friction of 21.6?. The sediment is contained in the deep sediment pit 7.6 m (25 ft long), 3.7 m wide(12 ft ) and 1.5 m deep(5 ft) in the dredge/tow tank that is 45.7 m long(150 ft), 3.7 m wide(12 ft), and 3.0 m deep(10 ft). The objectives of the study are to calculate the forces using existing theory and MATLAB program and compare the theoretical results to those measured in the laboratory. The effects of the depth of cut, direction of swing, and cutter rpm on the forces acting on the cutter head are evaluated. The forces on the cutterhead are determined through the use of a set of six load cells rated at 13.3 kN (3000 lb). The load cell measurements allow direct calculation of the forces on the cutter head through the use of static equilibrium equations with the assumption of a constant swing speed. Once the forces are determined the results can be scaled to fit an actual dredge and then be applied in the determination of dredge design characteristics. The study shows the ability of the theory to determine the forces within an order or magnitude. The theoretical forces allow design of a cutter using a factor of safety. The variability of the forces in the laboratory study shows the assumption that the cutting forces are generally steady is not always valid.

Author dc:creator

• Permenter, Rusty

Contributors dc:contributor

• Randall, Robert

• dredging
• dilatancy

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/1969.1/ETD-TAMU-2010-12-8767

OAI record oai:identifier

https://tdl-ir.tdl.org/server/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Atdl-ir.tdl.org%3A1969.1%2FETD-TAMU-2010-12-8767