Two-dimensional cut plan optimizationfor cutter suction dredgers

Optimal cut plans for cutter suction dredgers aim to maximize operational efficiency.Maximizing operational efficiency involves minimization of stoppage time resulting fromnon-productive dredger movements. To automate a systematic search for optimal twodimensionalcut plans for cutter suction dredgers two models with an adaptive simulatedannealing-based solution approach were developed.The first model, the dredge cut nesting model, optimizes irregular stock cutting problemswhere stencils represent dredge cuts and sheets represent dredging areas. Stencils arecollections of unit dredge cuts with dimensions related to an effective cutting width whichcan be achieved with the cutter suction dredger considered. The objectives of the dredgecut nesting model are to maximize sheet coverage and to minimize stencil overlap.Centroids of unit dredge cuts of final nest layouts are extracted and used as grid nodes inthe second model.The second model, the dredger routing model, optimizes asymmetric travellingsalesperson problems with turning costs. The objectives of the dredger routing model areto minimize total route length and sum of turning angles, and to maximize average linklength. A link consists of two or more route edges which are aligned with each other towithin specified limits.A significant result of this research is that an engineering application of both modelsshowed that two-dimensional cut plans for cutter suction dredgers can be systematicallyoptimized and that dredger routes with minimum turning costs can be found. However,results also showed that the dredger routing model is not yet sophisticated enough to findcut plans for cutter suction dredgers for which overall project execution time is minimal.