Performance of coastal circular bridge pier under joint action of solitary wave and sea current

Abstract

As an important transportation infrastructure, coastal bridges are widely established in coastal areas, the piers of which are always subjected to waves and currents and are prone to damage, especially under extreme marine conditions. Since ocean waves and currents coexist and twist with each other, it is necessary to take both them and their interaction into account to better understand the interaction between the pier and the marine environment. To reveal the interaction mechanism among waves, currents and piers under extreme marine conditions caused by hurricanes or tsunamis, the joint action of solitary wave and sea current on the piers are studied based on a numerical model with the immersed boundary (IB) method in this paper. The calculation capability of this model is verified and a series of simulation cases are systematically carried out depending on this model. The prominent factors of the environmental conditions including current velocity and wave height and the piers with different diameters and arrangements are considered. The flow field, the wave run-up, the velocity, the pressure and the hydrodynamic load on the piers are investigated, the results of which indicate that the total force on the pier under the joint effect of solitary wave and sea current is several times the sum of the forces under solitary wave and current. The higher the velocity of the sea current is, the more significant the wave and current coupling effect is. When the tandem pier is with the small gap, the forces on the streamwise and transverse tandem piers are smaller and larger than those on the single pier, respectively, and with the increase of the gap, the force on the tandem pier tends to be that on the single pier. The small gap in the streamwise tandem piers and the large gap in the transverse tandem piers are beneficial to the stability of piers.