Experimental Study On Scour At Abutment In Floodplain Condition

ABSTRACT:During the flood period, the floodplain is submerged by the water flows, resulting in the formation of overbank flow, which is different from the flow in the main channel. The overbank flow disturbed by bridge abutments located in the floodplain would cause local scour around the structures, causing high risk to bridge operation. So it’s of great importance to study the flow characteristics and scour depth around the abutments under overbank flow.This dissertation mainly focuses on local scour in vicinity of bridge abutment under floodplain river conditions and discusses the flow structure and floodplain scour depth around bridge abutments through theoretical analysis and flume tests. The main factors affecting the floodplain abutment scour depth were analyzed and the relationship between main factors and floodplain abutment scour depth was determined. The formula of maximum scour depth around the abutment in the floodplain was established by dimensional analysis and multiple regression method. Compared with the conventional formulae, most of the calculated values of the new formula are between Sturm’s and Melville’s values, and relatively close to the Dongol’s value, showing good credibility of the formula presented in this dissertation.