Field Measurements of Bridge Pier Scour in a Curved Channel

Pier scour is the most common cause of bridge failures, so the problem for the erosion of soil surrounding a bridge foundation has attracted extensive attention. The Jiaxing-Shaoxing Bridge (JSB) is located in Jianshan bend of the Qiantang River Estuary (QRE). The special flow structure and bed morphology of the bend makes the scouring characteristics of the piers particularly complex. Based on the results of Multibeam Echosounders for topographic surveying in recent six years, the scouring characteristics of pier foundation of a main navigation channel of the JSB are analysed in this paper. The results show that with the implementation of the reclamation project in the QRE area, the river channel has been gradually narrowed, coupled with the sharp reduction of the sediment entering the sea of the Yangtze River, the river regime swing in the QRE has changed significantly compared with that in the original design stage of the JSB. Under adverse river regime hydrological conditions, the riverbed erosional depth near the bridge is remarkable, and the local scouring depth of the pier is superimposed, which significantly will reduce the minimum elevation of the bed around the pier.