Author(s): R. J. Keller; P. Kong
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Keywords: No Keywords
Abstract: General scour is that component of the total scour at a bridge site arising from the overall effect of the flow constriction. In this study the problem is idealised by considering the constricted bridge site as a uniform long contraction. A computer progr am is developed to predict the temporal and spatial variation of the non-equilibri um scour in the contraction. In a series of tests, conducted to obtain data against which the model could be tested, armouring of the bed was observed, resulting from the use of a graded bed material. To accommodate the armouring process in the computer model, the characteristics of the armoured layer were empirically input. The results indicate that the computer model generally under-predicts the time-dependent scour in the contraction. A primary reason for this is that the characteristics of the armoured layer at equilibrium do not apply during the non-equilibrium phase. Despite this limitation the model is shown to predict the time-dependent behaviour of scour in a long contraction with reasonable accuracy.
Year: 1989