Journal of Agricultural Science and Technology
Journal of Agricultural Science and Technology
JAST
Agriculture
http://jast.modares.ac.ir
1
admin
1680-7073
2345-3737
10.22034/jast
en
jalali
1379
1
1
gregorian
2000
4
1
2
2
online
1
fulltext
en
Bridge Abutment Scour in Compound
River Channels
Most previous laboratory studies of local scour at bridge abutments were performed
in rectangular channels in which the distributions of flow velocity and bed shear
stress were considered uniform in the transverse direction. In reality however, bridge
abutments are usually located in the floodplain zone of rivers where velocity and
shear stress distributions are directly affected by the lateral momentum transfer. The
influence of channel geometry and lateral momentum transfer in compound flow field
on scouring phenomenon, however, has not been fully investigated and understood as
yet. This paper presents the results of an experimental study performed to investigate
the impact of both sediment size and lateral momentum transfer on local scour at
abutments terminating in the floodplain of a compound channel. It is shown that, by
accounting for lateral momentum transfer at small floodplain/main channel depth
ratios (yalH<0.3), estimates of maximum local scour depth are increased by up to
30% . In relation to the sediment size, earlier studies of scouring around circular
bridge piers proposed a limit for the relative size of sediment (pier diameter/median
size of bed material) beyond which the sediment size has no effect on the equilibrium
scour depth (Ettema, 1980; Chiew, 1984). The results of the current laboratory
studies, however, indicated that the limit established for circular bridge piers might
not be appropriate for the abutment case installed in the floodplain zones; further
studies are required to draw a more general conclusion regarding the effects of
relative grain size in the abutment case.
Scouring,Floodplain,Momentum transfer,Compound channal,Bridge,Abutment,Pier
95
106
http://jast.modares.ac.ir/browse.php?a_code=A-10-1000-4456&slc_lang=en&sid=23
S.
Kouchakzadeh
S.
Kouchakzadeh
100319475328460044894
100319475328460044894
Yes
Irrigation and Reclamation Engineering Department, University of Tehran, Karaj, Islamic
Republic of Iran.
Irrigation and Reclamation Engineering Department, University of Tehran, Karaj, Islamic
Republic of Iran.