Experimental study of wave loads on elevated pile cap of pile group foundation for sea-crossing bridges

Abstract

Elevated pile cap, which transits the load from sea-crossing bridge pylon to pile group, is always close to the sea level and suffering from extreme wave loadings. This paper describes a wave flume experimental program to investigate wave loads on the elevated pile cap of pile foundation for sea-crossing bridges. Two specimen configurations including isolated cap and cap with pile group were set up with different clearance heights. Wave forces on the cap, including horizontal and vertical force and moment, were measured simultaneously under five nonlinear regular wave trains. The effects of pile group, clearance height and wave height on wave forces on the cap were investigated. The experimental results show that the clearance height and wave height affect wave forces significantly. The largest horizontal force occurs when the cap is fully submerged, while the largest vertical force occurs when the bottom of the cap locates at still water level (SWL). As the wave height increases, the horizontal forces increase except for the fully submerged case and the vertical forces increase firstly but decrease when the wave height exceeds 0.18 m. Pile group increases the vertical uplift forces on the cap when the bottom of the cap locates above SWL.