Rehabilitation Of The Afsluitdijk

Abstract

The ‘Afsluitdijk’ is a 32 km long dam, which divides the Wadden Sea from the Lake IJssel. The dam has been rehabilitated by increasing the crest level to reduce the wave overtopping and reinforce the armour layers on the seaward and lake side of the dam. The Dutch Ministry of infrastructure and Water Management (Rijkswaterstaat division) commissioned Levvel, a consortium of BAM, Van Oord and Rebel, to carry out this renovation. Rijkswaterstaat encouraged contractors to offer innovative design solutions for the rehabilitation works as the dam is one of the icons in Dutch hydraulic engineering history. Levvel proposed two new armour materials to protect the dam against wave action and reduce the wave overtopping over the crest. A combination of Quattroblocks^® a product of Holcim Coastal and Levvel-blocs, internationally known as Xblocplus^® by BAM have both been introduced for the first time for the design of the dam. The application of innovative materials and/or techniques may incorporate uncertainties and because of the Afsluitdijk is one of the primary sea defenses preventing the Netherlands for flooding the contract included requirements for the Contractor to carry out physical model tests on the main failure mechanisms of the dam. Besides the contractual requirements, Levvel also used physical model tests to optimize the armour elements and the geometry of the dam. The verification of the design has been carried out with large scale 2D physical model tests in the Delta Flume of Deltares and small scale 2D model tests have been used to optimize design solutions.