Scour Reduction around Bridge Pier Using the Airfoil-Shaped Collar

• Published in: Hydrology
• Main Authors: Lav Kumar Gupta, Manish Pandey, P. Anand Raj, Jaan H. Pu
• Format: Article
• Language: English
• Published: MDPI AG 2023-03-01
• Subjects: scour; airfoil-shaped collar; efficiency of the collar; FLOW-3D; scour countermeasure; scour hole profile
• Online Access: https://www.mdpi.com/2306-5338/10/4/77

Scouring around the bridge pier is a natural and complex phenomenon that results in bridge failure. Failure of bridges have potential devastation and public safety and economic loss, which lead to political consequences and environmental impacts. Therefore, it is essential to countermeasure the scour around the bridge pier. This paper studies the effects of four different airfoil-shaped collars (i.e., <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>1</mn></mrow></msub></mrow></semantics></math></inline-formula> = 1.5<i>b</i>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></mrow></semantics></math></inline-formula> = 2.0<i>b</i>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>3</mn></mrow></msub></mrow></semantics></math></inline-formula> = 2.5<i>b</i> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>4</mn></mrow></msub></mrow></semantics></math></inline-formula> = 3.0<i>b</i>, where <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mi>c</mi></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mi>b</mi></semantics></math></inline-formula> are the diameter of the airfoil-shaped collar and pier, respectively) as a scour countermeasure. All the experiments are conducted under clear water conditions with uniform sediment and a constant water depth (<i>y</i>) of 10 cm. Airfoil-shaped collar is placed at four elevations, i.e., bed level, <i>y</i>/4, <i>y</i>/2 and 3<i>y</i>/4 above the sediment bed level. It is observed that the maximum percentages of scour reduction of 86, 100 and 100% occurred due to protection provided by the collar <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>3</mn></mrow></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>4</mn></mrow></msub></mrow></semantics></math></inline-formula>, respectively, at sediment bed level. So, collars <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>2</mn></mrow></msub></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>3</mn></mrow></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mi>b</mi><mrow><mi>c</mi><mn>4</mn></mrow></msub></mrow></semantics></math></inline-formula> are efficient at the sediment bed level. The profiles of scour hole show that the length of the transverse scour hole is greater than that of the longitudinal one. Numerical investigation of the morphological changes in sediment bed and scour depth contours is developed using the FLOW-3D for the pier with and without the airfoil-shaped collar.