Experimental Study on Local Scour Around Caissons with Different Shapes Under the Unidirectional and Tidal Currents

Abstract

Despite more and more attention has been paid to the study of local scour under the action of tidal current, seldom research on the effect of tidal current on the scour process around different shapes of caissons has been carried out so far. In order to investigate the time development of local scour around different shapes of caisson under the unidirectional or tidal current, a series of laboratory tests was conducted in a flume laboratory. Three shapes of caisson (circular, square and diamond) and two types of currents (unidirectional and tidal) were used to study the characteristics and time evolution of local scour. The main findings include: (1) the time evolution of scour depth under tidal current is slower and easier to be stable than that of unidirectional current; (2) the appropriate shape of water-facing surface on the caisson has the function of active scour measurement, which can influence the maximum scour depth around caissons with different shapes; (3) except for diamond caisson, the locations of the maximum scour depth around circular and square caisson will change under unidirectional current or tidal current; (4) square caisson is more sensitive to the effect of tidal current, diamond caisson is less sensitive.