Investigation of The Area of Around Bridge Abutment by A-Jacks to Protect Against Scour

Abstract

Scouring is a natural phenomenon that arises from the erosive action of flow field in the alluvial streams. Bridge failure caused by fully scouring of the piers and abutment makes completely clear the necessity of investigating in the case of scour prediction and ways to protect against it. One of the ways to reduce scour is utilizing the six-based elements (A-JACKS) around the abutment. In this study, the impact of the structure known as six-based elements on the control of the maximum scour depth of the bridge abutment was investigated as well as the scope of locating the six-based elements in order to safeguard the bridge abutment in front of the scour has been studied. The tests were performed with Froude numbers of 0.18, 0.208, 0.235, and 0.25 and in 4 placement scopes (W) of 4, 6.5, 8.5 and 10.6 cm. The scour was decreased one hundred percent in the Froude numbers of 0.18 and 0.208, and scopes of two-row (W2), three-row (W3) and four-row (W4). Froude number of 0.235 and scopes of three-row (W3) and four-row (W4) reduced fully the scour and the Froude number of 0.25 and scope range of four-row (W4) controlled 98.55% of the scour. In comparison with the performance of two scopes, the maximum six-based elements namely W3 and W4 were observed in the maximum Froude number that only have 7.47% difference in the reduction rate of the scour and have completely the same performance in the two Froude numbers of 0.18 and 0.208. In conclusion, it can be stated that the use of W3 range is most optimal mode of replacing elements around the abutment, because it has approximate performance to W4, but the cost and time of its construction is low.

Keywords

• a- jacks six legged elements
• palement area
• bridge abutment
• clear water