Implications of bed load transport mode on flushing flows in smooth pipe
Date
2015-03-25
Authors
Collinge, Sarah Lyn
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Abstract
The mode of sediment transport in a pipe has important practical implications on
self-cleansing flows. The two transport modes; discrete and collective, have
significantly different active storage volumes and effective grain velocities.
Excessive deposition of sediment occurs in the collective mode and can have
harmful environmental, social and economic effects. The conditions under which
each mode prevails and their effects on self-cleansing flows are explored in this
research report through laboratory investigation. Supply-limited bed load
experiments were performed resulting in two new relationships being developed
to predict the prevailing transport mode and the volume of active storage in a pipe
under certain conditions. A recommended methodology and a set of new design
graphs are presented as amendments to the current design guidelines for the
prediction of flushing flows rates and corresponding minimum durations for
sediment transport in a smooth pipe.