MINIMIZING OF SCOUR AROUND BRIDGE PIERS

Abstract

Bridges are one of the hydraulic structures, which constructed across open channels and are usually laid on some kind of supports that obstructs the channel flow. One of the most important considerations in the design and construction of the bridges is the scour around its foundation. Scour problems at bridge piers appear in variety of forms. Many of the bridge failures from flow, can be attributed directly to scour or undermining of the piers. Failure of bridge piers is a common occurrence, so the safe and economical design of bridge piers requires accurate prediction of the maximum expected depths of scour of the stream bed around them. Several efforts have been made to reduce scour around bridge piers in the last fifty years. In this study a new method was proposed to minimize the scour depth around bridge piers. The method depends on

reducing the flow stagnation in the front face of the pier using an opening on the front of the pier connected through the pier to two openings at the pier sides. The flow passes through these openings using pressure difference around the pier sides. This pressure difference attracts the flow to pass from the front opening to the side openings through the tube system connecting the openings this helps releasing the stagnation of .1e flow in the front of the pier as well as reducing the downward flow velocity component. A series of laboratory experiments were conducted in order to investigate the efficiency of the proposed method on minimizing of scour depth around a circular cylinder. Also an empirical formula for estimating the maximum scour depth was developed.