A flume study was conducted to investigate the influence of inflow seepage on localised pier scour through an alluvial channel bed. Eight tests were performed in which seepage inflow ranged from zero to three times the liquefaction velocity of the bed material. Channel Froude numbers ranged from approximately 0.40 to 0.80. The results indicated that for channel Froude numbers less than 0.70 and seepage velocity less than critical, the scour hole degraded by 20%. For channel Froude numbers less than 0.70 and seepage velocity greater than critical, the scour hole aggraded while the scour hole width increased as much as 2.25 times wider than scour hole widths observed for the no-inflow conditions. When the channel Froude number exceeded 0.70, scour hole depths were similar to the no-inflow conditions while the bed elevations adjacent to the scour hole significantly degraded.
Samenvatting