ABUTMENT SCOUR IN COHESIVE MATERIALS
Author: J.-L. Briaud, H.-C. Chen, K.-A Chang, S. J. Oh, X. Chen | Size: 37.45 MB | Format: PDF | Publisher: NCHRP | Year: 2009 | pages: 435
Bridge scour is the loss of soil by erosion due to flowing water around bridge supports. Bridge scour includes general scour and local scour. General scour is the aggradation or degradation of the riverbed not related to the presence of local obstacles. Aggradation is the gradual and general accumulation of sediments on the river bottom; one possible scenario is the existence of slope failures upstream leading to the formation of spoils in the river, the erosion of these spoils under higher velocities, followed by transport and deposition under lower velocities at the aggrading location. Degradation is the gradual and general removal of sediments from the riverbed; one possible scenario is the man-made straightening of a river course, a resulting increase in the water velocity and the associated increase in erosion. Local scour is the scour around obstacles to the water flow; it includes pier scour, abutment scour, and contraction scour. Pier scour is the removal of the soil around the foundation of the pier; abutment scour is the removal of the soil around the abutment at the junction between the bridge and the embankment; contraction scour is the removal of the soil from the bottom of the river due to narrowing of the river channel created by the approach embankments for the bridge.
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