Muhammad, Muhammad (2023) Analisis Pengaruh Gradasi Material Timbunan Terhadap Potensi Rembesan dan Stabilitas Tubuh Bendungan Gondang Jawa Tengah. Masters thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Bendungan Gondang merupakan salah satu bendungan yang terletak di Desa Gempolan dan Desa Ganten, Kecamatan Kerjo, Kabupaten Karanganyar, Provinsi Jawa Tengah. Bendungan Gondang merupakan bendungan tipe urugan zona inti tegak. Material penyusun timbunan bendungan utama terdiri dari empat zona yaitu zona inti, zona filter, zona random, dan zona riprap. Material random merupakan material yang dominan secara volumetrik terhadap tubuh bendungan itu sendiri. Akan tetapi terdapat perbedaan cukup signifikan pada gradasi material random antara spesifikasi teknik dan kondisi aktual yang cenderung lebih halus sehingga akan berdampak pada material properties di antaranya density dan sudut geser dalam. Pada penelitian ini menggunakan perangkat lunak SEEP/W untuk menghitung potensi debit rembesan yang akan terjadi pada tiga kondisi muka air (Muka Air Minimal, Muka Air Normal, dan Muka Air Banjir). Analisis stabilitas lereng timbunan di hulu dan di hilir disimulasikan dan dihitung faktor keamanannya dengan perangkat lunak SLOPE/W dengan variasi material properties material random (spesifikasi teknik dan kondisi aktual) pada tiga kondisi muka air bendungan yaitu (kondisi setelah selesai dibangun, kondisi muka air normal, dan kondisi rapid drawdown) dengan menambahkan faktor koefisien beban gempa OBE (Operating Basis Earthquake) dan MDE (Maximum Design Earthquake). Hasil analisis menunjukkan bahwa Bendungan Gondang masih dalam keadaan aman terhadap poteni debit rembesan yang terjadi yakni masih di bawah 1% dari rata-rata debit sungai yang masuk ke dalam waduk (0,7 m3/det). Hasil analisis stabilitas tubuh bendungan menunjukkan bahwa dengan material random sesuai spesifikasi teknis masih aman ditinjau dari tiga kondisi, muka air dengan dan tanpa pengaruh koefisien beban gempa. Hasil analisis stabilitas tubuh bendungan dengan menggunakan material random sesuai kondisi aktual menunjukkan beberapa kondisi yang menghasilkan nilai faktor keamanan kurang dari persyaratan sehingga tidak aman yakni pada kondisi pengaruh beban gempa OBE di sisi hulu pada kondisi paska konstruksi (muka air minimal) dan pada kondisi rapid drawdown adalah tidak aman berdasarkan syarat minimal faktor keamanan, begitu pula di sisi hilir pada kondisi muka air normal diperoleh nilai faktor kemanan yang lebih kecil dari syarat sehingga pada kondisi tidak aman. Kondisi sisi hulu pada pengaruh beban gempa MDE diperoleh nilai faktor kemanan lebih kecil dari persyaratan untuk paska konstruksi dan rapid drawdown. Sisi hilir mendapatkan nilai faktor keamanan lebih kecil dari persyaratan pada kondisi muka air normal dan rapid drawdown. Opsi penanganan untuk menaikkan faktor kemanan yakni dengan menggunakan counterweight pada bagian hulu dan hilir tubuh bendungan menggunakan material batu boulder sehingga dapat menaikkan faktor kemanan. Hasil analisis pada kondisi rapid drawdown dengan dan tanpa pengaruh koefisien beban gempa menunjukkan nilai faktor kemanan di atas persyaratan.
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Gondang Dam is one of the dams located in Gempolan Village and Ganten Village, Kerjo District, Karanganyar Regency, Central Java Province. The Gondang Dam is an upright core zone fill dam. The main dam embankment material consists of four zones, namely the core zone, filter zone, random zone, and riprap zone. Random material is volumetrically dominant material for the body of the dam itself. However, there is a significant difference in the random material gradation between technical specifications and actual conditions which tend to be finer so that it will have an impact on material properties including density and internal shear angle. In this study, SEEP/W software was used to calculate the potential seepage discharge that would occur in three water level conditions (Minimum Water Level, Normal Water Level, and Flood Water Level). The stability analysis of the upstream and downstream embankment slopes is simulated and the safety factor is calculated using SLOPE/W software with random material property variations (technical specifications and actual conditions) in three dam water level conditions, namely (construction conditions, normal water level conditions , and rapid drawdown conditions) by adding the OBE (Operating Basis Earthquake) and MDE (Maximum Design Earthquake) earthquake load coefficient factors. The results of the analysis show that the Gondang Dam is still in a safe condition against the potential seepage discharge that occurs, which is still below 1% of the average river discharge that enters the reservoir (0.7 m3/s). The results of the analysis of the stability of the dam body show that with random material according to technical specifications it is still safe in terms of the three water level conditions with and without the influence of the earthquake load coefficient. The results of the stability analysis of the dam body using random materials according to actual conditions show several conditions that result in a safety factor value that is less than the requirements so that it is not safe, namely under the influence of OBE earthquake loads on the upstream side in post-construction conditions (minimum water level) and in rapid drawdown conditions is unsafe based on the minimum requirements for the safety factor, as well as on the downstream side in normal water level conditions the safety factor value is obtained which is smaller than the requirements so that in unsafe conditions. The condition of the upstream side under the influence of the MDE earthquake load obtained a safety factor value that was smaller than the requirements for post-construction and rapid drawdown. The downstream side gets a safety factor value that is smaller than the requirements under normal water conditions and rapid drawdown. The treatment option to increase the safety factor is by using a counterweight on the upstream and downstream parts of the dam body using boulder stone material so that it can increase the safety factor. The results of the analysis on rapid drawdown conditions with and without the influence of the earthquake load coefficient show that the safety factor value is above the requirements.
| Item Type: | Thesis (Masters) |
|---|---|
| Uncontrolled Keywords: | Random material, Seepage, Stability, Geostudio 2021, Material Random, Rembesan, Stabilitas |
| Subjects: | L Education > L Education (General) |
| Divisions: | Faculty of Civil, Planning, and Geo Engineering (CIVPLAN) > Civil Engineering > 22101-(S2) Master Thesis |
| Depositing User: | Muhammad Muhammad |
| Date Deposited: | 02 Aug 2023 08:49 |
| Last Modified: | 23 Aug 2023 02:03 |
| URI: | http://repository.its.ac.id/id/eprint/101490 |
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