Alternatif Desain Geometri Tubuh Bendungan Leuwikeris Dengan Perubahan Parameter Material Timbunan Terhadap Slope Stability Dan Piping

Isnawati, Renata (2024) Alternatif Desain Geometri Tubuh Bendungan Leuwikeris Dengan Perubahan Parameter Material Timbunan Terhadap Slope Stability Dan Piping. Diploma thesis, Institut Teknologi Sepuluh Nopember.

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Abstract

Bendungan Leuwikeris merupakan bendungan urugan tipe zona dengan inti tegak, terletak diantara Kabupaten Tasikmalaya dan Kabupaten Ciamis, Provinsi Jawa Barat. Material penyusun Bendungan Leuwikeris berupa material tanah lempung (material inti), material filter (pasir halus dan kasar), serta material transisi (batuan andesit). Bendungan harus memenuhi kriteria minimum terhadap keamanan slope stability dan tidak memiliki potensi piping/erosi buluh akibat jumlah debit rembesan. Sering kali saat pelaksanaan konstruksi bendungan, terjadi perubahan parameter material timbunan. Perbedaan dapat terjadi. Bila sampel perencanaan kurang mendetail. Selain itu, faktor metode pelaksanaan timbunan dapat mempengaruhi perubahan parameter-parameter material. Nilai parameter-parameter mekanis tanah yang dapat berbeda diantaranya seperti : berat jenis, sudut geser, kohesi, dan koefisien permeabilitas. Penelitian ini dilakukan dengan membandingkan hasil pada model-model eksisting dan model alternatif. Model 1 dan model 2 merupakan desain eksisting yang dirancang oleh perencanaa tahun 2015 dengan data material eksisting atau material lapangan. Model alternatif yang disebut model 3 dan model 4. Bertujuan untuk menghasilkan alternatif bentuk geometri yang aman terhadap slope stability serta potensi bahaya piping/erosi buluh. Analisis dilakukan menggunakan software GeoStudio dengan tools SEEP W/ dan SLOPE W/. masing-masing pemodelan dilakukan saat tampungan kosong. Adanya muka air tampungan, serta saat terjadi rapid drawdown. Pada model-model analisis juga dilakukan pembebanan faktor gempa, sesuai dengan aturan pembebanan beban gempa pada bendungan urugan. Hasil analisis perhitungan menunjukkan. Bahwa pada model 4 dengan kemiringan lereng hulu 1:3 dan lereng hilir 1:2,8 memenuhi persyaratan angka keamanan pada stabilitas lereng dan aman terhadap potensi piping akibat debit rembesan yang terjadi. Safety factor terhadap stabilitas lereng pada kondisi tanpa gempa menghasilkan nilai yang memenuhi persyaratan. Pada kondisi kosong nilai safety factor hulu 2,795 dan hilir 1,910. Dengan kondisi muka air normal, safety factor hulu sebesar 2,764 dan hilir 1,797. Untuk kondisi muka air banjir Q 1000, menghasilkan safety factor hulu 2,783 dan hilir 1,866. Dan pada kondisi muka air banjir Q PMF, safety factor hulu 2,805 dan hilir 2,654. Serta pada kondisi rapid drawdown didapatkan safety factor hulu 2,788 dan hilir 1,708. Pada anailsis beban gempa OBE, model memenuhi syarat. Namun. Analisis dengan beban gempa MDE masih belum memenuhi persyaratan minimum, karena hal tersebut dilanjutkan analisis dengan cara alihan tetap Makdisi-Seed pada gempa MDE. Hasil analisis menunjukan bahwa model 4 masih memenuhi syarat deformasi maksimum yang terjadi dengan pembebanan gempa MDE. Kemudian, hasil analisis perhitungan pada kondisi MAN, MAB Q 1000, dan MAB Q PMF didapatkan sebagai berikut : 9,14-6 m3 /det; 1,23-5 m3 /det; 1,61-5 m3 /det. Sedangkan pada kondisi rapid drawdown nilai rembeasnnya sebesar 1,12-5 m3 /det.
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Leuwikeris Dam is an embankment dam with a vertical core, located between Tasikmalaya Regency and Ciamis Regency in West Java Province. The materials used for constructing the Leuwikeris Dam include clay soil (for the core), filter materials (fine and coarse sand). And transition materials (andesite rock). The dam must meet minimum criteria for slope stability safety factors and have no potential for piping/erosion due to seepage discharge. Often during dam construction, changes in the embankment material parameters occur. Differences can arise if the planning samples are not detailed enough. Additionally, embankment construction methods can influence changes in material parameters. The values of mechanical soil parameters that can vary include specific gravity, shear angle, cohesion. And permeability coefficient. The analysis method in this research involved comparing the results of existing models and alternative models. Model 1 and Model 2 are existing designs created by the planners in 2015 using existing material or field material data. The alternative models, referred to as Model 3 and Model 4. Aim to determine the most ideal geometric shape that is safe for slope stability and potential piping/erosion hazards. The analysis was conducted using GeoStudio software with SEEP/W and SLOPE/W tools. Each modeling was performed during empty reservoir conditions, presence of reservoir water level. And rapid drawdown. The models also included seismic loading according to the dam's earthquake load regulations. The results of the analysis indicate that Model 4, with an upstream slope of 1:3 and a downstream slope of 1:2.8, meets the safety requirements for slope stability and is safe against potential piping due to seepage discharge. The safety factor for slope stability under nonseismic conditions meets the required standards. Under empty conditions, the upstream safety factor is 2,795. And the downstream safety factor is 1,910. With normal water levels, the upstream safety factor is 2,764. And the downstream safety factor is 1,797. Flood water level with Q1000, the upstream safety factor is 2,783. And the downstream safety factor is 1,866. Under Flood water level Q PMF, the upstream safety factor is 2.805. And the downstream safety factor is 1,708. In rapid drawdown conditions, the upstream safety factor is 2,788. And the downstream safety factor is 2.581. Under seismic loading with an OBE, the model meets the requirements. However, the analysis under MDE loading does not meet the minimum safety requirements. As a result, further analysis using the Makdisi-Seed method for MDE seismic loading was conducted. The results show that Model 4 still meets the maximum deformation criteria under MDE seismic loading. Additionally, the calculated seepage discharge under normal water level conditions, 1000-year flood conditions. And PMF conditions are as follows: 9,14-6 m³/s, 1,23-5 m³/s. And 1,61-5 m³/s, respectively. Under rapid drawdown conditions, the seepage discharge is1,12-5 m³/s.

Item Type:	Thesis (Diploma)
Uncontrolled Keywords:	Bendungan Urugan, Bendungan Leuwikeris, Safety Factor, Slope Stability, Piping, Rembesan, GeoStudio, SEEP W/, & SLOPE W/ Embankment Dam, Leuwikeris Dam, Safety Factor, Piping, Seepage
Subjects:	T Technology > TC Hydraulic engineering. Ocean engineering > TC167 Dams, reservoirs
Divisions:	Faculty of Vocational > Civil Infrastructure Engineering (D4)
Depositing User:	Renata Isnawati
Date Deposited:	15 Aug 2024 06:44
Last Modified:	15 Aug 2024 06:44
URI:	http://repository.its.ac.id/id/eprint/112858

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