ANALYSIS SEEPAGE AND SLOPE STABILITY FOR DAM: CASE STUDY JLANTAH DAM IN JATIYOSO, KARANGANYAR REGENCY, CENTRAL JAVA

• Main Author: Aulia Rahma, Aryandi
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/80233
• Institution: Institut Teknologi Bandung

Jlantah Dam is one of the National Strategic Projects (PSN) whose construction began in 2019 and is targeted to be completed by December 2023. This dam is located in the Tlobo and Karangsari villages, Jatiyoso District, Karanganyar Regency, Central Java. With a storage capacity of up to 11.96 million m3 , this dam is designed as a zonal embankment dam with a random sand gravelly zonal vertical core. The Jlantah Dam is expected to irrigate an area of 1494 ha and provide raw water at a rate of 150 liters/second. The construction of the dam not only promises significant benefits but also poses potential hazards in the event of failure. Therefore, a study is needed to assess the safety of the Jlantah Dam under various conditions, including seismic events. The study includes seepage analysis using the Slide2 software and dam stability analysis using the slide2 software by reviewing the dam's geometry. The data used as input in these analyses include soil permeability coefficients, internal friction angles, soil cohesion, and soil density based on field investigations and laboratory analyses that began in 2017. In the seepage analysis, manual calculations were also performed using the Casagrande method to compare the results obtained from Slide2. From the seepage analysis using slide2, the Jlantah Dam is classified as safe against leakage, with the largest flow rate of 8,8264 x 10-3 m 3 /s occurring at the normal water surface elevation. The seepage flow rate is inversely proportional to the slope safety factor. In the dam stability analysis using Slide2, there are several unsafe conditions with the lowest safety factor of 0.81 occurring on the upstream slope at the normal water surface elevation due to the SEE (Safety Evaluation Earthquake) loading. The analysis results yield the largest permanent displacement value of 95 cm with an earthquake magnitude of Ms = 8.25; Y/H = 0.25. This value is still smaller than the required permanent displacement value of 250 m, indicating that the dam slope remains in a safe condition.