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Wim C.D. Kortlever

4 records found

Authored

The Impact of Density Differences on the Hydraulic Design of Leveling Systems

The Case of New Large Sea Locks in IJmuiden and Terneuzen

Journal article (2023) - Helena I.S. Nogueira, A.J. van der Hout, Tom S.D. O'Mahoney, Wim C.D. Kortlever

Recent constructions of large sea locks in the Netherlands at IJmuiden and Terneuzen have been accompanied by extensive hydraulic research, including physical scale model tests which took into account the effects of density differences across the lock heads during leveling ope ...

A novel design method for wave-induced fatigue of flood gates

Journal article (2022) - T.N.J. Kleiberg, Orson Tieleman, Marco Versluis, Wim C.D. Kortlever, Erik ten Oever, Bas Hofland

This paper presents a novel design method to predict fatigue of flood gates due to dynamic wave loading. The accumulation of fatigue damage is predicted probabilistically over the entire lifetime of the structure rather than with a set of normative events. Load events are defined using a joint probability distribution of historical wind and water level data. The random phase-amplitude model is employed to obtain realisations of the wave state for every combination of environmental conditions. Linear wave theory and pressure-impulse theory are used to predict both quasi-steady and highly dynamic wave pressures. The stress response of the structure is predicted with a hybrid semi-analytical and finite element model. By applying a mode matching technique the fluid-structure interaction is solved in a computationally efficient manner. This facilitates the large number of simulations required for a comprehensive fatigue analysis without making concessions in the physical modelling. The fatigue damage is then evaluated with the linear Palmgren-Miner method by applying a rainflow algorithm. A Monte Carlo analysis is performed to estimate the expected fatigue lifetime of the structure. The modular structure of the model routine allows for easy adaptation to other situations where fatigue due to hydrodynamic loading is of interest. The design method is applied to a case study of a flood gate with an overhang inspired by the situation at the Afsluitdijk. Non-fundamental modes are taken into account without simplification of the fluid-structure interaction process and found to be governing for the fatigue damage for the studied case. Moreover, the interference of vibrations due to consecutive wave impacts is shown to have a significant influence on the outcome of the fatigue assessment. For the case study, the design method leads to a 10-20% reduction of the governing fatigue damage compared to a method commonly used in practice. At specific locations on the flood gate fatigue damage is found to be underestimated by current design methods. The presented design method is therefore found to be a significant improvement.@en

Effect of density differences on the forces acting on a moored vessel while operating navigation locks

Journal article (2018) - Helena I.S. Nogueira, P.P.D. van der Ven, P.P.D. van der Ven, Tom S.D. O'Mahoney, Alexander De Loor, A.J. van der Hout, A.J. van der Hout, Wim C.D. Kortlever

This paper investigates the effect of density differences on the forces acting on a moored vessel during lock operations, focusing on the effect of the position of the moored vessel in the lock chamber in the presence of density currents. The extensive scale-model research per ...

Contributed

Stability of rock-based emergency measures based on the Grave Weir calamity

Master thesis (2018) - H. van Oorschot, Sebastiaan N. Jonkman, Bas Hofland, G.M. Smith, Wim C.D. Kortlever

On the 29th of December 2016 a large Rhine ship loaded with 2000 ton benzene sailed through the weir at Grave, located in the river Meuse in the Netherlands. The accident created a large gap in the weir and within 12 hours the upstream water level decreased by a maximum of 3 meters. Due to this decreased water level shipping was limited, houseboats were skewed and there was a risk of instability of the river banks and upstream weirs.

Several alternative measures were considered to close the damaged part of the weir in order to reinstate the upstream water level, and make it possible to repair the weir. Finally it was decided to build a rock-fill dam behind the damaged part of the weir which closed nearly 55% of the weir. Due to this closure, all the discharge had to pass the weir through the remaining 50 meters-wide southern opening. As a result of this upstream water levels were set-up faster than during normal operations. High upstream water levels, relatively high discharges and a low downstream water level caused extreme flow situations with even supercritical flow (hydraulic jump) over the bed protection. At weir Grave the existing bed protection was injected with colloidal concrete and an additional ballasting sill, made of 3-6t carefully placed stones and 4t rock nets was constructed, to prevent additional damage to the bed protection.

In this study the stability of the measures which were used to prevent additional damage to the bed protection are analyzed. This study focusses on the 3-6t carefully placed stones, rock net sill and the bed protection behind it. The 4t rock nets were not able to withstand discharges up to 450m3/s and flow velocities up to 7.0m/s due to the internal instability of the small rock material inside the nets. The 3-6t stones were able to withstand discharges up to 850m3/s and flow velocities up to 6.7m/s. Due to the fact that the stones were carefully placed, the stability increased. A stability correction factor (Φsc) up to 0.73 can be used instead of 1.5 as prescribed by Pilarczyk for stones on the edge of a bed protection. The 40-200kg bed protection with colloidal concrete has withstood extreme flow velocities up to 7.2m/s whereby only small damages occurred. The 40-200kg quarry stones without colloidal concrete also showed limited damages after the 850m3/s flood wave and depth averaged flow velocities up to 5.2m/s. The conclusions of the analysis are projected to the other six weirs in the Meuse and to the possible calamities which could occur here.

In order to perform the stability analysis of the bed protection measures at weir Grave, the Meuse and the seven weirs in the Meuse were analyzed. The Meuse is a controlled river in the Netherlands and is kept navigable by a seven weir system. These weirs differ in dimension, head loss and operating system. Based on the characteristics of these weirs one simplified fictive weir is chosen and tested on the consequences of various calamities. Besides, also the long-term maintenance strategy is considered in this study. Both have the similar result that part of the weir is non-operational for a longer period, discharge capacity is limited and all highly variability in occurring discharges is possible.

In this study the consequences to the water management of the fictive weir are considered. To guarantee an upstream water level to a certain target level, panels and slides are removed from a weir for increasing discharge. If part of the weir is not available due to a closure, panels and slides have to be removed earlier than in a normal situation. Therefore, the limit discharge, the discharge for which the weir is completely open, is reached earlier for the different closure situations. If the limit discharge is reached, the upstream water level starts to increase. In this thesis the discharge, according to an upstream water level equal to the flood plain level, is the maximum considered discharge. For further increasing discharge, and water levels, the flood plains start to discharge water and the flow velocities downstream of the weir will no further increase.

The flow velocities for three closure situations and three discharge situations are considered in this study. It turned out that the flow velocities which are calculated in this thesis are always lower than the flow velocities which occurred during the Grave weir calamity. Therefore it is concluded that the measures used during the Grave calamity, are all applicable to the other weirs in the Meuse. But lastly is must be concluded that due to a relative large closure of a weir (>50%), severe flow circumstances like supercritical flow, can occur. In case of a future calamity or long-term closure, it is advised to minimize the closure width as much as possible.