GERUSAN DI SEKITAR ABUTMEN DAN PENGENDALIANNYA PADA KONDISI ADA ANGKUTAN SEDIMEN UNTUK SALURAN BERBENTUK MAJEMUK

Abstract

Scour is erosion due to water flow on the alluvial channel bed and channel wall. In fact, scour happened in the bridge abutment is total scour, that is a combination between local scour, general scour, and constriction scour. This research aim is to find the impact of screen and pile to scour process and the depth of scour near abutment on live-bed scour condition. This research was carried out using recirculation flume. The channel model was a compound channel and using steady-uniform flow. The abutment model were Spillthrough type (ST) and Wing-Wall (WW) type. Screen and pile variation were used as scour control model. The depth of scour near abutment was measured in each 6 hours running, The research result shows that live-bed scour condition is the most critic condition, and the depth of scour on this condition is maximum. The depth of scour is mostly affected by Reynold and Froude number of channel flow. The screen which was placed on the upstream of abutment at optimum distance 1,75 Lb from abutment ace gave highest reduction of scour depth compared with other distances. In the case of 1-piled screen placed on channel bank at 1,75 L, it gave the best scour reduction, i.e. 26,68% on live-bed scour condition. In general, the scour pattern happened around abutment is the same, either using protection or without protection. It can be seen on the scour contour pattern. The scour contour pattern in this research shows similar pattern witch shaped a halp horseshoe with wide up at the side of abutment perpendicular to the stream and lengthten up at downstream with the shallower scour depth.