|Research Home | Hydraulics Home| |This report is an archived
publication and may contain dated technical, contact, and link
information| Publication Number: FHWA-RD-03-083 Date: June 2003
This chapter presents results of pier- and abutment-scour
experiments to study effects of clay content on clear-water
scour. Results show that the presence of even a small amount of
cohesive material may reduce scour considerably. To quantify the
impact of clay content, scour in clayey sands is expressed as a
fraction of scour measured in noncohesive materials through a
clay content reduction factor, Kcc. It is shown that Kcc is a
function of clay content. It is also shown that different clay
minerals have varying impacts on reducing bridge scour. Scour at
bridges has been studied extensively in the past for noncohesive
sediments. The currently adopted scour estimation methodologies
were basically developed from laboratory experiments conducted
in sand or gravel beds. No method for scour depth estimation is
available to acc