Bridge Pier Scour in Clay-Sand Mixed Sediments at Near-Threshold Velocity for Sand |
| |
Authors: | Koustuv Debnath Susanta Chaudhuri |
| |
Affiliation: | 1Associate Professor, Dept. of Applied Mechanics, Bengal Engineering and Science Univ., Shibpur, Howrah 711103, West Bengal, India (corresponding author). E-mail: debnath_koustuv@yahoo.com 2Project Research Fellow, Dept. of Science and Technology, Government of India, Howrah, 711103 West Bengal, India; and Doctoral Student, Bengal Engineering and Science Univ., Shibpur, Howrah, 711103 West Bengal, India. E-mail: susantachaudhuri2003@yahoo.co.in
|
| |
Abstract: | Local scour at circular bridge piers embedded in a clay-sand-mixed bed was investigated in laboratory flume experiments. The effects of clay content, water content, and sand size on maximum equilibrium scour depth, equilibrium scour hole geometry, scouring process, and time variation of scour were studied at velocities close to the threshold velocities for the sand in the clay-sand mixture. It was observed that clay content and water content were the key parameters that effect the scouring process, scour hole geometry, and maximum equilibrium scour depth. The bridge pier scouring process in clay-sand mixtures involved different dominating modes for removal of sediment from scour hole: chunks-of-aggregates, aggregate-by-aggregate, and particle-by-particle. Regression-based equations for estimation of nondimensional maximum scour depth and scour hole diameter for piers embedded in clay-sand mixtures having clay content of <40% and water content of <40% were proposed as functions of pier Froude number, clay content, water content, and bed shear strength. |
| |
Keywords: | Sediments Erosion Piers Flumes Open channels Sand hydraulic Water content Shear strength |
|
|