Indonesia Conference Directory

Abstract Groundsill is a structure in the form of a weir that is built across the river which aims to reduce the speed of the current and increase the depositional discharge in the downstream part of the bridge pole structure. Supercritical flow and sand mining at downstream of the bridge can endanger the pillar. Scouring around the bridge pillars can endanger the girder which of course endangers the bridge as a whole. The aims of this study were to analyze the stability of the Groundsill Bridge in the Garang River channel on the force of rolling, sliding, eccentricity, carrying capacity of the soil, and piping. This research uses survey method. Data collection methods used were observation and secondary data. Analysis of the data used were (1) rainfall design of 50 years return period; (2) design flood discharge with a 50 year return period; (3) the forces acting on the groundsill, and (3) the groundsill stability. The results of the study indicate that: (1) the groundsill were safe against rolling forces under normal flow and flood flow conditions; (2) groundsill was safe against shear forces under normal flow and unsafe during flood flow conditions; (3) groundsill was safe against eccentricity in normal flow conditions and unsafe in flood flow conditions; (4) the carrying capacity of the groundsill subgrade were safe against forces that occur during normal conditions and unsafe during flood conditions; and (5) groundsill was safe against piping under normal flow and flood flow conditions. The recommendation that can be submitted was the groundsill of the bridge in the Garang River channel should be equipped with energy dissipation, besides that the dimensions of the groundsill body are enlarged.