Özet:

Groins are the most popular techniques for riverbank stabilization that are constructed along the channel bank to locally change river conditions, thereby creating a flow condition that promotes navigability and diverts the flow away from the bank. The scour around groin head play a very important for their performance. No systematic experiments have been conducted to study the scour around bell mouth groin. An experimental study was undertaken in a 45.6m long and 2.45m wide laboratory water basin to investigate the local scour around a non-submerged bell-mouth groin structure. A total number of 12 test runs were performed for different flow conditions. Three different discharges and four different angles with non-submerged groin condition were considered in the present study. Therefore, Twelve tests were conducted of which six had a water depth of 14 cm and the rest six had a flow depth of 18 cm. All tests were conducted for 8 hours duration in clear water condition. In order to avoid the ripple formation, the coarse sand with d50 = 0.75 mm was selected as bed material. Scour depth for 90ο angled groin was observed to be the maximum and for 135ο it was the minimum. The time to reach maximum scour depth was found to vary with discharge and angle of attack. The study also revealed that maximum scour depth and deposition pattern changed for the case of different test runs. Scour depth varied with velocity variation of flow, and an increasing tendency of scour depth has been observed with increasing flow intensity. Maximum scour depth shows an increasing trend with increasing Froude number.

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