GERUSAN LOKAL DI SEKITAR DUA ABUTMEN DAN UPAYA PENGENDALIANNYA
ABSTRACT: Flow in an
open channel with
a mobile bed
is generally accompanied
by a transport
of sediments, which
is a result of interaction between
flow and sediment.
An obstacle, such
as pier or
abutment, positioned in the
flow, will locally alter
the flow in the
channel, causing erosion (scour)
and possibly deposition
in the vicinity
of the pier
or the abutment. More
than one abutment
is possibly installed
with series positions
in river. This
group of abutment
will exhibit a mutual influence on the hydraulic behavior and on
scouring. Until now research on the single abutment was considered, however research using
two abutments is
extremely scarce. Research of
scour around two
abutments was conducted in Hydrology
and Hydraulic Laboratory,
PSIT Gadjah Mada
University. Flow was
clear-water scour and steady
uniform flow. A
tilting sediment recirculating flume
with 10 m
long and 60 cm
wide was
used. Flow is run in
movable bed using
sediment with d50=0.73 mm and
s=2710
kg/m3. Two abutments
were installed in
the side of the
channel. These were
separated variously. Scour
depth around the
two abutments was
measured using point
gauge. Researches were also
done for a horizontal
ring-formed shield placed
on the abutments
prove to diminish
the scour depth. Research results
on scour at two abutments indicate that the scour depth of the front abutment
is greater then the one of the rear abutment. Detailed results are: when the
two abutments touch each other, the scour depth of the front abutment is
not influenced; when the
two abutments are
separated, the scour
depth of the
front abutment begins to increase
but eventually falls
out. A maximum
increase of scour
of the front
abutment, reach 30
% compared with
the scour depth of
a single abutment, is
found when the separation of the two
abutment, a/Dp, is
about 3; When the
two abutments are much separated, a/Dp≈12, the front abutment is not
influenced; The scour depth of the rear abutment is always smaller then the one
of the front abutment; The scour depth between the two abutments diminish
rapidly and is negligible for a/Dp
> 12 ; when
ring-formed is placed
on the abutment,
scour depth of
the front abutment
is reduced reached 36,7 %.
Keywords: local scour,
abutment, preventive work
Penulis: Rawiyah. Th.Husnan,
dan Bambang Yulistiyanto
Kode Jurnal: jptsipildd070012
