Interference between pier models and its effects on scour depth

Abstract

Excessive scouring of sediment around bridge piers plays a major role causing failure of waterway structures. To prevent scouring around bridge piers, it is necessary to determine the maximum scour depth. In the past, researchers have conducted extensive laboratory work around flow structures with the help of scaled models. But most of the work has been carried out around an isolated pier and the work around a group of piers is relatively much lesser. To fill up the gaps in information, an experimental study was conducted in a recirculating water flume 15 m long, 0.4 m wide and 0.6 m high containing uniform sediment of mean size, d 50 = 0.30 mm. Experiments on cylindrical pier models of size 42 mm were run at a velocity equal to 0.89 times the critical velocity, u c. Three different arrangements i.e. Tandem, Side by Side and Staggered have been used to analyze the effect of spacing and orientation on scour. From the initial observations it was concluded that, in the case of Tandem arrangement when the spacing between the piers was 16 times the diameter of the pier and more, both the piers showed independent behavior. But if the spacing between the bridge piers is 0D, then both the piers behave like a single pier and the scour depth was found to be 41% greater than that of a single pier. However, when the clear spacing was greater than 1.5 times for side by side and 2.5 times for staggered arrangement, the piers behaved independently.

Influence of Multi-Cross Structures on the Flood Discharge Capacity of Mountain Rivers in the Yellow River Basin

“…A numbers of studies have been conducted to discover the influence of bridges, dams and gates on flood discharge capacity of rivers. Malik et al [19] conducted a series of physical model experiments to study the influence of the number and spacing of piers on the backwater region of a bridge. Subedi et al [20] simulated bridge pier sizes and flows considering various river configurations, to study the effect of bridge pier closure on the upstream flood.…”

Investigation of Local Scouring around Hydrodynamic and Circular Pile Groups under the Influence of River Material Harvesting Pits

“…Moreover, they provided an equation to estimate the scour depth. Malik and Setia [8] conducted a laboratory study of scouring around bridge pile groups in three arrangements: Piles adjacent to each other, aligned in the flow direction, and in a triangular arrangement. For piers arranged in a row, if the distance between the piers exceeds 16 pier diameters, the piers behave as independent entities.…”

An Analysis of Local and Combined (Global) Scours on Piers-on-Bank Bridges

“…They concluded that the local scour process is mainly governed by pier spacing, the horseshoe vortex and reinforcement elements around the piers. Several laboratory studies have been carried out to investigate the relationship between pier spacing and maximum scour depth around two piers in a side-by-side arrangement [24][25][26]. To the best of the authors' knowledge, there is no literature on the effect of scouring between two side-by-side piers with consideration of the loading on piles.…”