Kornwerderzand guard lock

The Kornwerderzand guard lock is a steel rolling gate that is designed to operate at high tide. The lock is part of the 32-km-long Afsluitdijk. This dike is currently undergoing a major renovation and reinforcement operation to continue to protect the Netherlands from rising sea levels.

The Kornwerderzand guard lock is a steel rolling gate that is 58 m long, 8 m wide and 14 m high, and it moves on a rail track. This lock closes the waterway over a full width of 53 m. The lock is set up in a gate chamber to spring into action during high tide.

Structural design of the rolling gate

The rolling gate is supported by two undercarriage mechanisms. The rolling gate has an internal open construction with three internal horizontal frameworks. The 8 m wide rolling gate is also equipped with a 14.3 m high water retaining skin plate and has a span of 55.8 m.
For the design of the Kornwerderzand guard lock, it was important that:

• the risk of non-availability of the flood barrier remains as low as possible
• the guard lock is capable of withstanding a storm that may occur once every 10,000 years;
• the associated maximum leakage rate remains within permissible limits

Based on these principles, it was decided to design a rolling gate as simply as possible with components that have a low risk of failure and where maintenance requirements are limited.

Risk-driven design choices are consequently a guiding principle in the design of this rolling gate, which is why the rolling gate is also equipped with a jet system, for example. Unlike traditional retaining equipment, the rolling gate is designed without an air box. This does not only reduce the weight of the rolling gate to 926 tons, there are also fewer components that can fail at the time the rolling gate is supposed to operate.

Structural design of the undercarriage mechanism

Due to the absence of an air box in the rolling gate, it presented a challenge for the undercarriage mechanism to be able to transfer the very high wheel stresses to the underlying rail structure. As a result, the wheels of the undercarriage mechanism are relatively large compared to a rolling gate of similar dimensions.

Another unique aspect of the undercarriage mechanisms is that an innovative concept was selected, whereby sensitivities to execution tolerances of both the undercarriage mechanisms themselves and the rail system on which they run are eliminated as much as possible. This was accomplished by, among other things, a central shaft that allows both wheel axles to rotate independently of each other and, consequently, make the undercarriage mechanism very torsionally flexible.

Finite element analysis

Several software packages were used for the design, focusing on EE analyses in Sofistik and Ansys.

The initial preliminary design used a simple bar girder model to quickly and easily optimize the design.
Further detailed calculations were carried out based on a fully detailed slab model of the entire rolling gate.

EE models in Ansys were used for specific detailed studies, such as calculations of heat developments in the slider, Hertz contact pressure calculations and collision analyses.

Would you like to learn more?

Read more technical details about the design of the rolling gate and accompanying undercarriage mechanism in the article below from Bouwen met staal.