Quantitative analysis of scour around inline and eccentric pier under fixed inflow depth

Abstract

Scouring is a natural phenomenon generated by the passage of water in a river or stream. It is most noticeable in alluvial materials, but severely worn rock can also be vulnerable under specific conditions. Every year, numerous bridges fail, resulting in the loss of lives and property as well as some uncomfortable circumstances for transportation systems. Because of this, bridge designers are increasingly considering the flow-soil-structure interaction. Urban setting around the world is getting densely populated and facing heavy traffic with increased number in vehicles. This opens the scope for the construction of new bridges beside already existing old ones and thus arises the need to study the interference of inline and eccentric piers. Therefore, a thorough investigation of scour depth around inline and eccentric piers in such conditions is highly desirable. In this present study, the hydrodynamic consequences of different eccentric arrangements on scouring were investigated. Erosion and deposition patterns were studied around the front and eccentric piers at different time intervals along the flume. In these series of experiments two identical circular piers are used to conduct six experiments with fixed inflow depth and varying the eccentricity between two piers in each experiment. The longitudinal spacing between the upstream pier and the eccentric pier was also kept fixed. Six different eccentricities were used to run the experiment for 12 hours to obtain resultant scour. A fixed discharge of 27 Lps and clear water condition was also maintained throughout the experiments. The results obtained from the series of experiments was carefully analyzed to obtain the best arrangement for eccentricity which would be beneficial aspect for bridge designers.