Piping Potential due to springs in dam (Case study : Titab Dam)

Abstract

The dam is one of the water infrastructures that can function as conservation, utilization, and control of thedestructive power of water. Titab Dam is one of the dams in Indonesia that has multifunction as irrigationwater, raw water and hydropower. This dam is a type of rock fill dam with an upright core which has a peaklength of 210 m, a width of 12 m, and a height of 78 m from the deepest foundation. This dam was built withrelatively complex geological conditions and landslides occurred on the spillway walls and springs were foundin the landslides so it was necessary to analyze the potential for piping due to the presence of springs. Thisstudy examines the potential for piping due to the influence of springs near the dam. The study was conductedbased on instrument observations during the inundation period from 2016 to 2019. The analysis was carriedout by calculating the acceptance criteria (KP) for seepage and seepage index (Qi) to determine seepagebehavior in the dam body and a safety factor analysis (FK) for piping hazards was carried out by comparingthe hydraulic gradient based on piezometer instrumentation readings and the hydraulic gradient of the dambody core material. Based on the calculation of the seepage acceptance criteria and the seepage index, theseepage that occurs in the Titab Dam is not safe because it exceeds the requirements, the average seepageoccurs is 6.350 > 0.56 liter/minute/m and Qi > 1. However, the analysis of the safety factor of piping hazardis still safe that is equal to 8,390 > 4.