Samenvatting

Throughout this thesis, a competitive durable reinforcement design for the Mastenbroek-IJssel reinforcement project is developed and modeled. In 2024 the Drents Overijsselse Delta Water Board began with the exploration phase of the Mastenbroek-IJssel reinforcement project as 10.8 km of the IJssel dike no longer met the safety standard of 1:3000 years. In order to refine the scope of this research a durable reinforcement alternative was developed for the sub-section of the dike with the lowest overall durability. To identify the least durable dike sub-section a qualitative analysis was made considering durability scores for each section. Dike section De Naters proved to be the most
brittle of the sub-sections considering the current cross-section, present failure mechanisms and the previously proposed reinforcement alternatives. For this research an explicitly durable reinforcement design was created for dike section De Naters.

Literature reviews, site visits and expert workshops aided in developing three preliminary durable reinforcement designs. A multi-criteria analysis was made in collaboration with the WDOD, where each preliminary design was evaluated based on spatial impact, technical feasibility, costeffectiveness and sustainability. As a result from expert meetings, the alternatives were refined into one design for further research. The design combines soil reinforcement of the upper and inner talud, a clay soil improvement on the inner talud, a paved bicycle path on the crest, and a secondary dike built roughly 100 m landward of the primary dike.
Stability calculations performed using D-Stability show that both dikes in the durable reinforcement design meet the required safety factor of 1.24. 3Di was used to model breach simulations of the durable reinforcement design and a brittle design which both meet the design standard of 1:3000 years. The results of the flood simulations were inputted into the SSM-2017 software to determine the overall flood consequences. The overall flood risk of the durable reinforcement design is 5.3 times less than that of the brittle variant. The difference in flood risk is expressed as a robustness index. The robustness index is used to reevaluate the design safety standard, which is used when
considering the durable reinforcement alternative. That allows for design optimizations without reducing the overall safety. When construction costs and residual risks are considered, the durable variant proves to be roughly 0.63 million euros more cost-effective than the brittle reinforcement alternative. It should be considered that this cost estimate does not include the land acquisition required for either alternative. This thesis presents a transferable method for considering durability as an optimization in dike design in addition to the specific results of this case study. By distinguishing brittle from ductile failure behaviors and analyzing the effects, dike reinforcement solutions can be developed; maximizing social benefit and ultimately improving flood-risk management in polders.