Basic Study on Scour around Bridge Piers and Its Prevention.

Igarashi, Tamotu; Nishida, Kouzou

doi:10.1299/kikaib.58.1990

Cited by 1 publication

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“…The same tendency was observed in Cases 2 and 7, where the water level history was iterated using Type 1 model. In summary, when the local scouring progresses under the condition of iterated rise and fall of the water level for Type 1 model, a deep zone of the local scour hole, which has a slope gradient similar to the repose angle in water, is formed as an inverted cone affected by downflow due to the horseshoe-shaped eddies around the bridge piers, as reported in previous studies, until the maximum local scour depth reaches the equilibrium state [27][28][29]. After the maximum scouring depth reaches the equilibrium state, the top soil layer in the local scour hole, which has a slope gradient smaller than the repose angle in water, is scoured away by the scouring force of the water flowing into the local scour hole, and the erosion phenomenon progresses.…”

Section: Type 1 Modelmentioning

confidence: 87%

Effects of Dynamical Change in Water Level on Local Scouring around Bridge Piers Based on In-Situ Experiments

Kadono

KATO

Okazaki

et al. 2021

Water

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To evaluate the stability of bridge piers affected by the local scouring, the existing formulas for estimating the maximum local scour depth have been developed based on the results of experiments conducted under a constant water level. However, the applicability of these formulas to the cases where the water level rises and falls, such as a water level change in a real river, is not clear. In this study, water flow experiments were conducted on cylindrical and oval bridge pier models to investigate the effect of iterated water level change on the progression of local scour around piers. Results of experiments with cylindrical and oval pier showed that the local scour depth and length increased by an iterated action of the water level change; however, these values converged after the number of iterated actions reached a certain time. The local scour length at upstream of the bridge pier was approximately 1.8 times larger than the theoretical value, which was calculated through the local scour depth and angle of repose in water. The local scour length is an important parameter for defining the streambed protection zone, which is one of the measures against local scour, and we showed that the streambed protection zone needs to be defined more widely.

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Section: Type 1 Modelmentioning

confidence: 87%