Q. How to design Shape of guide bunds?
Alignment of guide bunds converging on the upstream was considered by Bell, Spring and Gales to allow for the waterway obstructed by piers on bridge line.
With such a shape, flow may separate after passing round upstream curved heads leading to shoal formation on flanks near the bridge axis rendering end bays inactive. Divergent guide bunds were conceived by Haigh and Spring to mitigate tendency of separation. The distance between the worst loop of the river and the approach bank however gets reduced and shoal formation in the centre in the wide section some time occurs. Symmetrical and parallel guide bunds were proposed by Spring and Sethi as depicted. When provided with upstream curved heads of sufficiently big radius, this shape of guide bunds is found to prevent separation of flow along flanks and help in effecting equitable distribution of discharge across the bridge section.