Experimental study of flow structure around two in-line bridge piers

Abstract

Previous investigations indicate that local scouring is one of the most common causes of waterway bridge failure. The scour mechanism around bridge piers is complicated by the interaction of flow and structure. To explore the local scouring process, it is therefore essential to study the flow–structure interaction around bridge piers. Most previous studies have been based on this interaction around a single pier; however, in practice, many bridges are wide and comprise a number of piers aligned in the flow direction that together support the loading. In this study, a particle image velocimetry technique was used to investigate two-dimensional flow–structure interaction around two in-line bridge piers with different spacings. Various influencing flow characteristics including turbulence intensity, turbulent kinetic energy and Reynolds stresses were calculated in different vertical planes around the bridge piers. Results indicated that the flow characteristics around two in-line bridge piers are very different than for a single pier and the spacing between two in-line piers significantly influences the flow characteristics, particularly in the rear of the piers. Furthermore, for spacing in the range of 2 ≤ L/D ≤ 3, stronger turbulence structures occurred behind pier 1 and, as a result, a higher scour depth can be expected around pier 1.