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document
Baken, N. (author), Van Boven, E. (author), Feunekes, B. (author), Hoffmans, J. (author), Mesgar Zadeh, S. (author)
conference paper 2008
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van Beek, V.M. (author), Hoffmans, G.J.C.M. (author)
The prediction of backward erosion piping is important for safety assessment of dikes in the Netherlands, where subsurface conditions are prone to this erosion mechanism. In the current assessment methodology, the adapted Sellmeijer rule is in use. In combination with the national safety philosophy and uncertainty in input parameters, this model...
conference paper 2017
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Hoffmans, G.J.C.M. (author), Booij, R. (author)
Excessive local scour can progressively undermine the foundation of a structure. Because complete protection against scour is too expensive generally, the maximum scour-depth and the upstream slope of the scour hole have to be predicted to minimize the risk of failure. In 1961 a systematical research 'tY'ith respect to scour holes started in the...
conference paper 1993
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Verheij, H.J. (author), Hoffmans, G. (author), Dorst, K. (author), Van de Sande, S. (author)
Granular filters are used for protection of structures against scour and erosion. For a proper functioning it is necessary that the interfaces between the filter structure, the subsoil and the water flowing above the filter structure are stable. Stability means that there is no transport of subsoil material through the filter to the water above...
conference paper 2012
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Bosman, G. (author), Van der Meer, J.W. (author), Hoffmans, G. (author), Schüttrumpf, H. (author), Verhagen, H.J. (author)
Recently, formulae have been derived for maximum flow depths and velocities on the crest and inner slope of dikes or levees at wave overtopping. Two independent physical model test programs in different wave flumes showed, however, a large difference in the results. The present paper clarifies this discrepancy and shows that the empirical...
conference paper 2008
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Baken, N.H.G. (author), Van Boven, E. (author), Hoffmans, J. (author), Hollemans, W. (author), Van De Lagemaat, W. (author)
conference paper 2007
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Verheij, H.J. (author), Hoffmans, G. (author), Hardeman, B. (author), Paulissen, M. (author)
Destructive wave overtopping tests have been performed at more than 20 dike sections in the Netherlands using the Wave Overtopping Simulator to simulate the overtopping waves. The tests show the combined behaviour of turf and substrate up to mean wave overtopping discharges of 75 ?/s per m, meaning wave volumes up to 5,500 ?/m with flow...
conference paper 2012
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Hoffmans, G.J.C.M. (author)
doctoral thesis 1992
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Hoffmans, G. (author), Verheij, H.J. (author)
This paper discusses scour without bed protection, such as propeller scour, two-dimensional horizontal, three-dimensional horizontal scour generated by free jets downstream of gates and outlets, two-dimensional vertical and three-dimensional vertical scour. The flow velocities in two- and three-dimensional propeller and free jets are briefly...
journal article 2011
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Van der Meer, J.W. (author), Van Hovern, A. (author), Paulissen, M. (author), Steendam, G.J. (author), Verheij, H.J. (author), Hoffmans, G. (author), Kruse, G. (author)
Dit rapport is voortgekomen uit de resultaten van een vier jaar durend destructief onderzoek naar de erosiebestendigheid van binnentaluds onder golfoverslagbelasting. Dit onderzoek is onder andere uitgevoerd met de golfoverslagsimulator. In het onderzoek is kennis ontwikkeld over de wijze waarop golfoverslag de grasbekleding van een binnentalud...
report 2012
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Hoffmans, G.J.C.M. (author)
A two dimensional mathematical model DUCT, which is based on a parabolic boundary layer technique, using finite elements, is proposed to predict the flow and turbulence field in complicated geometrical conditions, where recirculating flow may occur. Numerical results of the DUCT-model are compared with k-eps-predictions as well as laboratory...
report 1988
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Verheij, H.J. (author), Hoffmans, G. (author), Den Adel, H. (author), Akkerman, G.J. (author), Giri, S. (author)
A desk study has been carried out regarding interface stability of granular filter structures. Actually, the project focuses on two particular aspects: (1) interface stability as function of the thickness of the filter layer consisting of standard armourstone gradings, and (2) interface stability of gravel mixtures with a wide gradation The...
report 2009
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Hoffmans, G.J.C.M. (author)
Het handboek ontgrondingen beoogt een instrument te zijn om de grootte van lokale ontgrondingskuilen rondom brugpijlers, kribben, achter drempels met of zonder bodembescherming, uitlaatconstructies, strandmuren, strandhoofden, etc. te voorspellen. Met het handboek kunnen ontwerpers en adviseurs een eerste schatting van het ontgrondingsproces...
report 1994
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Uittenbogaard, R.E. (author), Hoffmans, G.J.C.M. (author), Akkermans, R.J. (author)
report 1998
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Van der Meer, J.W. (author), Hoffmans, G. (author), Van der Hoven, A. (author)
Within the framework of WTI, Research and Development of Flood Defence Assessment Tools (Wettelijk Toetsinstrumentarium), which is called in Dutch: WTI-2017 "Onderzoek en ontwikkeling landelijk toetsinstrumentarium", research was carried out to develop an erosion model for grass in the wave run-up zone consistent with the current model in use...
report 2014
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Hoffmans, G.J.C.M. (author)
In the nineties, the stability of the Dutch river dykes along the Rhine could not be guaranteed. Hence many people were evacuated. None of the dykes failed and the damage was mainly restricted to the evacuations costs. Several recommendations were made to anticipate the treats of the near by future. Within this framework a prototype experiment...
report 2002
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Hoffmans, G.J.C.M. (author)
The general purpose of this research project is to model mathematically the scour-hole downstream of a structure (2-D). The model has to simulate the development of the scour as a function of time. Basically two models are necessary namely a flow model and a morphological model. The latter has to describe the bed- and suspended load and the...
report 1988
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Hoffmans, G.J.C.M. (author)
In the Netherlands hydraulic engineering structures are not only designed, but are also managed and maintained (M&M). In the nineteen-nineties in the United States during periods of high water scores of bridges collapsed, because American law forbids the use of bed protection around bridge piers and moreover, no maintenance plans were available....
report 2006
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Hoffmans, G.J.C.M. (author)
Some information is given how to use the scour model DUCT-SUSTRA (Hoffmans, 1991). The scour model predicts the morphological process in scour holes or trenches and consists of two separated sub-models: a flow model DUCT and a morphological model SUSTRA. The flow model is based on the equation of continuity and the momentum equations for...
report 1991
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Steendam, G.J. (author), Hoffmans, G. (author), Bakker, J. (author), Van der Meer, J.W. (author), Frissel, J. (author), Paulissen, M. (author), Verheij, H.J. (author)
Overview of overtopping with focus on river dikes. Realtin with sod density.
report 2012
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