Abstract

With the escalating expansion of constructional activities into the rivers, estuaries, coastal and offshore areas, the need for understanding the morphodynamic and hydraulic changes in these environments can hardly be overestimated. These structures will change their surrounding wave and current conditions and lead to local scouring of certain seabed, resulting in structural damage. Local scour depth is one of important facts in the design of large bridge basis in coastal environment. In this paper, according to the sediment conditions near the bridge, different scale models are used to study local scour around bridge piers and abutments under steady flow, or irregular wave-current action. The characteristics of scour geometry in different conditions are described. The results show that the equilibrium scour depth due to current – wave interaction is about 7~14% greater than the depth due only to stead current. It shows that the effects of waves on the local scour depths might be little as the current dynamic conditions are very strong. Therefore it is necessary to analyze and compare the dynamic conditions of wave and current in prediction of scour depth around practical bridge piers. The paper puts forward some suggestions helpful for design of coastal bridge basis.

Keywords: bridge piers; wave-current; local scour