Preference-Based Decision Support for Quay Wall Assessment

Abstract

In response to the European Commission's initiative to shift freight transport from road to inland waterways, there is a need to expand the capacity of inland ports to accommodate larger cargo ships. This expansion requires lowering the water bottom, which will increase the forces exerted on the quay walls. The quay walls should therefore be reinforced by applying structural adjustments, for minimal costs and environmental impact. The goal of this thesis is therefore to develop a decision support tool, which is able to directly determine the preferred configuration of structural adjustments. To maximise the aggregated preference of all stakeholders involved while satisfying the systems constraints, the a-priori design optimisation method of the Preferendus is applied.

The tool, developed using computational science, uses Python because of its capability to automate repetitive calculations. It integrates with the program D-Sheet Piling that is used for specific sheet pile calculations. The tool is designed to be used during the preliminary design phase, enabling quick assessment of potential reinforcement adjustments and facilitating insight into the preferred solution. It evaluates three main strategies for quay wall reinforcement: lowering active soil stress, increasing passive soil stress, and enhancing pile stability. The tool uniquely focuses on maximising the aggregated preference of involved stakeholders and is capable of evaluating failure mechanisms of sheet piles.

It is tested on three case studies, all located in the industrial harbour Loven in Tilburg. The results show that the tool effectively proposes which structural adjustments are applicable to create a sheet pile design that satisfies. The thesis concludes by drawing specific conclusions for each structural adjustment considered in the project. Moreover, it concludes that the development of a decision support tool has been successful. In particular, the tool enhances efficiency in sheet pile calculations, offers detailed insights into the environmental and financial impact of adjustments and enables the direct determination of the preferred configuration of structural adjustments. This eliminates the need to choose the preferred configuration from a number of designed variants, which is the current approach.

Additionally, the thesis recommends to conduct a follow-up research on the applicability of underwater anchors, which have shown significant structural potential. Furthermore, it recommends to conduct laboratory tests to potentially improve the cohesion and angle of internal friction of soil layers. If those soil parameters can be improved, no structural adjustment may be necessary to reinforce quay walls at all.