Fahlefi, Muhammad Syah (2025) Alternatif Desain Perubahan Kemiringan Peluncur Spillway Bendungan Jragung Untuk Mengatasi Permasalahan Geoteknik. Other thesis, Institut Teknologi Sepuluh Nopember.
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Abstract
Bendungan Jragung yang terletak di Provinsi Jawa Tengah dibangun dengan fungsi sebagai penyedia air baku, irigasi, dan pengendalian banjir. Salah satu komponen penting dalam bendungan adalah spillway yang berfungsi untuk mengalirkan air saat muka air banjir guna mencegah limpasan yang dapat merusak tubuh bendungan. Namun, pada tahap konstruksi ditemukan adanya lapisan batuan lunak (koluvial) di area pondasi spillway yang memunculkan potensi kelongsoran lereng dan ketidakstabilan struktur pelimpah. Kondisi ini menimbulkan permasalahan geoteknik yang memerlukan penanganan lebih lanjut, khususnya terkait stabilitas lereng dan struktur spillway. Oleh karena itu, proyek akhir ini bertujuan untuk merencanakan kemiringan peluncur yang aman dan stabil sehingga dapat mengatasi permasalahan geoteknik.
Metode yang digunakan meliputi analisis hidrologi, hidraulis, dan geoteknik. Analisis hidrologi dilakukan dengan metode HSS Nakayasu untuk menentukan debit banjir rencana Q1000 dan QPMF, didukung oleh data DAS dan tata guna lahan. Analisis hidraulis digunakan untuk menentukan elevasi muka air pada spillway. Evaluasi stabilitas lereng dilakukan menggunakan metode bishop dan fellenius, sedangkan stabilitas struktur spillway dianalisis terhadap potensi guling, geser, dan rembesan. Sebagai perlakuan terhadap permasalahan eksisting, dilakukan perubahan desain kemiringan peluncur dari 1:2 (27derajat) menjadi 1:3 (21derajat) dan penerapan pondasi dalam berupa tiang bor berdiamater 1 m sedalam 15 m sebagai upaya perkuatan struktur.
Hasil analisis menunjukkan bahwa perubahan desain mampu meningkatkan kestabilan lereng dan struktur pelimpah. Faktor keamanan lereng pada kondisi eksisting sebesar 1,154 meningkat menjadi 2,27 setelah dilakukan perubahan desain dengan merubah kemiringan disertai dengan perkuatan struktur. Hal ini membuktikan bahwa desain alternatif terbukti mampu meningkatkan kestabilan lereng dan keamanan struktur terhadap beban vertikal maupun lateral, serta memastikan spillway dapat berfungsi optimal. Dengan demikian, hasil dari proyek akhir ini diharapkan dapat memberikan rekomendasi alternatif desain yang lebih aman dan efektif, serta dapat menjadi referensi dalam perencanaan spillway pada kondisi geoteknik serupa di masa mendatang.
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The Jragung Dam, located in Central Java Province, was built with the function of providing raw water, irrigation, and flood control. One of the important components in the dam is the spillway which functions to drain water when the water level is flooded to prevent runoff that can damage the dam body. However, at the construction stage, it was found that there was a layer of soft rock (colluvial) in the spillway foundation area which gave rise to the potential for slope landslides and instability of the overflow structure. This condition poses geotechnical problems that require further handling, especially related to slope stability and spillway structures. Therefore, this final project aims to plan a safe and stable launch slope so that it can overcome geotechnical problems.
The methods used include hydrological, hydraulic, and geotechnical analysis. Hydrological analysis was carried out using the Nakayasu HSS method to determine the flood discharge of the Q1000 and QPMF plans, supported by watershed and land use data. Hydraulic analysis is used to determine the elevation of the water level on the spillway. Slope stability evaluation was carried out using the bishop and fellenius methods, while the stability of the spillway structure was analyzed against the potential for rolling, shearing, and seepage. As a treatment for the existing problem, the design of the glide slope was changed from 1:2 (27degrees) to 1:3 (21degrees) and the application of the inner foundation in the form of drill poles with a diameter of 1 m and 15 m deep as an effort to strengthen the structure.
The results of the analysis showed that the design changes were able to improve the stability of the slope and overflow structure. The slope safety factor in the existing condition of 1.154 increased to 2.27 after a design change by changing the slope accompanied by strengthening the structure. This proves that alternative designs have been proven to be able to improve slope stability and structural safety against vertical and lateral loads, as well as ensure that spillways can function optimally. Thus, the results of this final project are expected to provide recommendations for safer and more effective design alternatives, and can be a reference in spillway planning under similar geotechnical conditions in the future.
| Item Type: | Thesis (Other) |
|---|---|
| Uncontrolled Keywords: | Spillway, Bendungan Jragung, Stabilitas Lereng, Geoteknik, Pondasi Dalam. Spillway, Jragung Dam, Slope Stability, Geotechnics, Deep Foundation. |
| Subjects: | T Technology > TC Hydraulic engineering. Ocean engineering > TC555 Spillways. Energy dissipation. Hydraulic jump. |
| Divisions: | Faculty of Vocational > Civil Infrastructure Engineering (D4) |
| Depositing User: | Muhammad Syah Fahlefi |
| Date Deposited: | 01 Aug 2025 07:51 |
| Last Modified: | 01 Aug 2025 07:51 |
| URI: | http://repository.its.ac.id/id/eprint/125702 |
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