STUDI GERUSAN DAN PERLINDUNGANNYA DI HILIR KOLAM OLAKAN BENDUNG TIPE USBR-I
ABSTRACT: In the
downstream of a
weir, especially in
stilling basin, there
is a phenomenon
called hydraulic jump
caused by flow change
from supercritical flow
to sub critical
flow. The hydraulic
jump in weir
stilling basin causes bed
scour, particularly in the downstream of weir that is not protected.
Therefore, laboratory study of scour and its countermeasure in the downstream
of weir is required. This study was
conducted at Hydraulic Laboratory of Surakarta River Research Centre using
recirculation flume. The recirculation flume dimensions were : length = 24 m;
width = 49 cm; and height = 60 cm. The bed material of recirculation flume was
fine sand (diameter of sieve = 2 mm)
with 20 cm thickness layered along the flume. The slope of flume was
0.004, and it was assumed that there was
no sediment load in the upstream of weir. This study used weir model USBR-I. The model was placed about
± 9 m from the upstream. The experiment was conducted using 8 discharge
variation running and 3 protection variation running. The result shows
that the maximum scour depends on flow velocity, shear velocity, and
flow height in the downstream of stilling basin. In addition, it is also affected by
Reynold number and
gravitation (as Froude
number). These parameters
are interdependent significantly. Furthermore, there
is significant scour
reduction in the
downstream of stilling
basin which is
protected using either
¼ Lmaks rip-rap, ½ Lmaks rip-rap, and Lmaks rip-rap. In addition,
protection using Lmaks length rip-rap can protect scour with smallest scour
depth. However, scour
is still happened
in the downstream
of stilling basin
although there is
protection along Lmaks.
Keywords: hydraulic jump, scour depth, scour
protection, rip-rap
Penulis: Jaji Abdurrosyid ,
Gurawan Jati Wibowo, M. Nursahid
Kode Jurnal: jptsipildd090006
