Onderwerp: Bezoek-historie

A hydraulic and morphological criterion for upstream slopes in local-scour holes

Dit onderwerp bevat de volgende rubrieken.


G.J.C.M. Hoffmans; Ministry of Transport, Public Works and Watermanagement, Rijkswaterstaat, Road and Hydraulic Engineering Division = Ministerie van Verkeer en Waterstaat, Rijkswaterstaat Dienst Weg- en Waterbouwkunde



Scour is a natural phenomenon caused by the flow of water in rivers and streams. Scour occurs naturally as part of the morphological changes of rivers and as result of structures man-made. Several types of scour can be distinghuished. Experience has shown that due to sand or flow slides or micro instabilities at the end of the bed protection, the scour process can progressively damage the bed protection, leading eventually to the failure of the hydraulic structure for which the bed protection was meant. The lenght of the bed protection depends on the permissible amount of scour (maximum scour depth and the upstream scour slope) and the geotechnical structure of the soil involved. In the scope of the Dutch Delta works, a systematical investigation of time scale for two and three-dimensional local scour in loose sediments was conducted by Delft Hydraulics and the department of Public Works (Rijkswaterstaat). From model experiments on different scale and bed materials, relations were derived in order to predict the steepness of the upstream scour slope. Sincethe predictebility of these relations is poor, especially for prototype conditions, a theoretical study concerning upstream scour slopes is carried out.



Report nr. W-DWW-93-255
With ref.

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