AbstractsEngineering

The second Delta-committee (September 2008) foresees difficulty in resolving flood safety issues for Rotterdam and Dordrecht if high river runoffs are still running through the New Waterway. A new safety issue, induced by climate changes, lies in the combination of closed sea defensives and relatively high river runoffs at the same time. A research proposal is made towards an Usually Open Occasionally Closed (UOOC) water-system around Rotterdam and Dordrecht. (In Dutch; Afsluitbaar Open Rijnmond, AOR.) This concept diverts high river runoffs during storm situations towards the Southern rural parts of the delta. Four large movable water barriers, located in the main waterways and navigation channels, are required within the UOOC concept. This plan calls for an innovative barrier designs. First of all, the purpose of the movable barriers in combination with their required width is exceptional. Second, barrier designs are outdated and relatively new, light-weighted and maintenance low, materials are not applied. Third, the life-time of a structure is determined by social aspects. The UOOC barriers are located at the edge of urbanized areas and a multi functional structure could enhance benefits and social acceptance. Up till now, hydraulic structures are mainly mono functional structures. Within this thesis the objective is to make an innovative design for one of the UOOC barriers. The design should be ready for the water problems of the 21st century, ready for a 21st century society and constructed by the latest materials. An objective of this thesis is to investigate an innovative barrier design; an ‘open fabric’ movable water barrier (similar to a parachute). This is in contradiction to a ‘closed fabric’ barrier like an inflatable dam. The thesis is a technology assessment of an ‘open fabric’ barrier and designing with synthetic materials to lower the barrier costs. First of all the locations, water-management strategies, corresponding boundary conditions, required dimensions and the costs of the UOOC barriers are discussed. A fabric barrier is suitable for the UOOC concept because of the possible fast construction and low maintenance, which is favourable because the barriers are located in the busiest waterways of the Netherlands. Design issues concerning fabric water barriers and specific ‘open fabric’ barriers are discussed. Different ‘open fabric’ design concepts are generated and discussed. A subdivision can be made in single, mattress, modular and stepped water barriers. A proposed preliminary design is made where a cable-stayed bridge is combined with a single screen attached to the deck over the entire waterway of 210m wide. The screen diverts the hydraulic loads with ropes towards the deck and the abutments. It is stored under the deck and unfolds with the help of cables. It is concluded that the structure is technical and economical feasible, however, a small scale model test is recommended for the closing-system of the barrier and to test its dynamic behaviour. Also an optimization should be…