de Ruyter, Marcus J.M.
Two-dimensional cut plan optimization
for cutter suction dredgers
University of Southampton, School of Civil Engineering and the Environment,
Optimal cut plans for cutter suction dredgers aim to maximize operational efficiency.
Maximizing operational efficiency involves minimization of stoppage time resulting from
non-productive dredger movements. To automate a systematic search for optimal twodimensional
cut plans for cutter suction dredgers two models with an adaptive simulated
annealing-based solution approach were developed.
The first model, the dredge cut nesting model, optimizes irregular stock cutting problems
where stencils represent dredge cuts and sheets represent dredging areas. Stencils are
collections of unit dredge cuts with dimensions related to an effective cutting width which
can be achieved with the cutter suction dredger considered. The objectives of the dredge
cut 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 in
the second model.
The second model, the dredger routing model, optimizes asymmetric travelling
salesperson problems with turning costs. The objectives of the dredger routing model are
to minimize total route length and sum of turning angles, and to maximize average link
length. A link consists of two or more route edges which are aligned with each other to
within specified limits.
A significant result of this research is that an engineering application of both models
showed that two-dimensional cut plans for cutter suction dredgers can be systematically
optimized 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 find
cut plans for cutter suction dredgers for which overall project execution time is minimal.
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