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Abstract
Scour around bridge is considered one of the server problems facing hydraulic engineers. It is considered one of the most critical problems in bridge pier design because of dynamic nature of scouring. Neither the worst case nor the net effect can be easily predicted, where such design requires an estimation of max. Scour depth at the pier during construction of a bridge
This thesis studies the scour depth around circular pier at IMBABA bridge as one of the important bridges Cross River Nile in Cairo-Egypt. Also to study the long-term scour upstream the bridge at circular pier. A field data were measured in[1992] . Which contains 29 measured cross-sections including measured velocity at three cross-sections U.S and D.S and twelve samples of bed material were taken to construct a mobile bed model? Recent filed data had been measured in [1996]. Which contain 19 cross-sections upstream and downstream the bridge.
An experimental study using an undistorted Model, clear –water scour condition with sandy bed has median diameter d50 = 0.268 mm conducted in Hydraulic research institute (HRI) , Ministry of water resources and irrigation (MWRI) . Twelve runs were conducted including three different value of flow depth (Y). The experimental results were used to investigate five empirical formula for estimating maximum scour depth at circular pier as a function of discharge, velocity. Froude number, densimetric Froude number and normalized velocity . Also experimental results compared with common formulae. The measured cross sections in 1992 and 1996 were used to compare bed level. It was found that no significant change in the bed level
Hopefully, this thesis makes a contribution to the problem of estimating the local scour depth around