In the Netherlands two large sea locks are currently being built: the new lock of IJmuiden, providing access to the port of Amsterdam and the new lock of Terneuzen, providing access to the port of Ghent. The design process for the levelling system of these navigation locks encompasses extensive hydraulic studies where both numerical and physical models are used in combination with a field measurement campaign. This paper describes part of the physical scale model research and the field measurement campaign that have been carried out, focussing on the forces on the moored vessel in the lock chamber that develop during the lock-exchange. An overview of the design process of these two new sea locks in the Netherlands is presented by Kortlever et al., 2018 and the role of numerical models in the design of the leveling system of the new lock of Terneuzen is addressed by Mahoney et al., 2018.
A physical scale model facility was built at Deltares to simulate the complete leveling cycle of both locks. Since both the new lock of IJmuiden and Terneuzen are sea locks, a density difference over the lock will be present and for both locks the density current leads to dominant forces on the moored vessel during leveling and lock-exchange. The overall objective of the scale model research was to determine the leveling times that could be achieved for the considered leveling systems and to also study the lock-exchange that occurs after the gate is opened. To that end, the physical scale model has been equipped with movable gates that open automatically after leveling. It has been shown that the forces on the vessels in the lock chamber, as a result of the density current after opening of the gate, will often exceed the forces during leveling.
In the scale model, the lock chamber, lock heads, the leveling system and also parts of the approach harbors are represented. A predetermined density difference over the lock is maintained by adjusting the density of the approach harbors between tests. The approach harbors have been equipped with movable weirs to set the water levels in the approach harbors to the desired level. Vertical density profiles have been determined at several locations in the scale model by measuring conductivity and temperature. Next to this also water levels, flow velocities, positions of valves and gates and forces on the vessel have been measured. In total more than 200 measurement channels have been logged simultaneously.
Simultaneously to the physical scale model work, a field measurement campaign was conducted in which forces on vessels in the Noordersluis of IJmuiden were measured during the lock-exchange. The Noordersluis is presently the largest lock of the IJmuiden lock complex, and with main dimensions of 400 m x 50 m it is comparable in size with the newly to be built lock in Terneuzen (427 m x 55 m), but significantly smaller than the new lock of IJmuiden (545 m x 70 m). On basis of a comparsion between results of the field measurement campaign and physical scale model results, it was comcluded that in the future situation larger forces on vessels may be expected than currently experienced in the present locks. These results help pilots to prepare on how to handle the larger ships in the future largest locks in IJmuiden, which will be in operation in 2019, and in Terneuzen, which will be in operation in 2022.
The presented physical scale model studies and field measurements yielded new insights into the dominant processes that are important in lock-exchange processes of sea locks. The results of these studies have been used to determine requirements for lock operations for the future largest locks in the Netherlands, at IJmuiden and Terneuzen.
References:
Numerical simulations of two types of longitudinal filling system for the New Lock at Terneuzen, T. O’Mahoney, A. Heinsbroek, A. de Loor, W. Kortlever, 34th PIANC world congress, Panama 2018, may 7-12.
Engineering the Levelling Systems of the Sea Locks in The Netherlands; Taking into Account the Effects of the Density Difference, W.C.D. Kortlever, A.J. van der Hout, T. O’Mahoney, A. de Loor, 34th PIANC world congress, Panama 2018, may 7-12.