Numerical Modelling of Seepage Potential on the Dadahup-G1/A5-B4 Road, Central Kalimantan, Indonesia

Abstract The Dadahup-G1/A5-B4 road is part of a central government project in Central Kalimantan to support food estate activities in the Dadahup Swamp Irrigation Area. The road is built on the embankment of the primary and secondary irrigation canals. The road is built on top of soil fill from sedimentation in the canal. The soil is dominated by silty clay. Silty clay is characterized by low density, high water content, and limited drainage ability. The soil easily compresses or loses volume when subjected to loads. Varying water levels in the channel can cause seepage from the primary channel across the roadway to the channel on the other side. High water content can also cause stability and infiltration problems that need to be maintained. The purpose of this study was to determine the seepage potential and its effect on the stability of the roadbed. The subject of the study was water level fluctuations. The variables considered include channel water level, groundwater level, and soil permeability. The method used the numerical analysis model of the GeoStudio program with SEEP/W to analyze seepage on the embankment road. The research findings indicate that the higher the water level, the greater the seepage discharge of the water level at the upstream face and the lower the seepage discharge of the water level at the downstream face. Based on the criteria for accepting seepage in the embankment body, the current condition of the embankment is still in a safe condition. The safety factor at the maximum, mean, and minimum water level conditions meet the requirements (SF>4). The research results also show that the higher the water level, the lower the safety factor. However, to confirm the results obtained, further analysis is needed regarding the study of the potential risk of landslides impacting road embankments.