Abstract
Scour process at the abutment of bridge is influenced by the contraction of the stream flow specially when the abutment immureaneffectivewidth of the stream flow,also the shape of the abutment has an important effects onthescour depth at the abutment.In this paper a series of laboratory experiments were carried outto study the effect of contraction ratio and abutment shape on the scour and its maximum depth at the abutment.Threeshapes of abutments with three-contraction ratio with differentflow rateswere used.The result of the experiments showed that the circular shape and (30o) angle abutments reduce scour compared with that, which was, occur at the rectangular abutment.The reduction of scour depth with circular shape is about (22%) where that with (30o) angle is about (27%),also a dimensionless general empirical formula was createdfor thecalculation the scour depth by using the (SPSS 11.5) Statistical program a Coefficient (R2=0.933) of determination.
