Document Type : Research Paper
Civil Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.
Bridges when it crossing rivers often required multiple piers for support. One of has a limited investigation is the impact of piers on scouring and morphological aspects when a bridge crossing sharp-bend of river. Consequently, it is crucial to investigate the hydraulic behavior of water flow in these areas due to the presence of these piers. In present study, an experimental program was conducted on a laboratory flume featuring a two-pier bridge within a 180-degree (sharp) bend to accomplish this. The piers were strategically positioned at 90 and 150 degrees within the bend. The results indicated that the bridge within the 90o, under the threshold intensity condition, led to significant local scour depths around the piers. Specifically, the scour depths were found to be 1.80 and 1.15 times the width of the pier for the piers close to the outer and inner banks, respectively. The discharge increased from 240 l/min to 280 l/min while maintaining the same intensity of 0.85, resulting in a symmetric local scour depth at the pier near the outer bank. In contrast, the local scour depths in response to the piers in the 150o were considerably lower; at the threshold with a discharge of 280 l/min, the scour depths were measured to be 0.65 and 1.18 times the pier width for the inner and outer piers, respectively. Similar bed morphology was observed when the bridge was positioned at 150o for two discharge values (280 and 240 l/min) with the same intensity of 0.85. The findings showed that an increase or decrease in discharge value, with a constant intensity, did not influence the local scour depth and its extension around the pier close to the outer bank, indicating that the intensity component was more significant than the discharge.
- Maximum scour depth, is 1.8 times the pier width for the bridge at 90o and much lower at the pier at 150o
- The change of discharge value with the same intensity creates symmetric morphology vicinity of the piers
- The findings showed that the intensity component was more significant than the discharge
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