Lestari, Febby Sekar Dwi and r: Dr. Eng. Andre Primantyo H., ST., MT. and Dr. Eng. Tri Budi Prayogo, ST., MT. (2021) Evaluasi Dimensi dan Stabilitas Tanggul Kali Lamong di Kabupaten Gresik Jawa Timur. Sarjana thesis, Universitas Brawijaya.
Abstract
Kali Lamong memiliki luas Daerah Aliran Sungai (DAS) sekitar 720 km2 yang berada di Propinsi Jawa Timur. Penggunaan daerah sempadan sebagai permukiman warga di sepanjang Kali Lamong turut menjadi penyebab banjir, padahal menurut Peraturan Menteri PUPR No. 28/PRT/M/2015, garis sempadan untuk sungai bertanggul di kawasan perkotaan minimal berjarak 5 meter dari kaki luar tanggul sepanjang alur sungai. Dampak dari meluapnya Kali Lamong dirasakan oleh masyarakat yang tinggal di sepanjang bantaran sungai setiap tahunnya hal ini menyebabkan sawah, akses jalan raya, jalan pedesaan, dan sekolah terendam. Hal tersebut menyimpulkan bahwa pembuatan tanggul yang memenuhi syarat secara teknis menjadi sangat krusial demi menghindari bencana banjir yang lebih parah dan meluas. Pada kondisi banjir ekstrem dengan aliran sungai yang kuat, kejadian keruntuhan tanggul tanah akibat erosi (erosion) atau gerusan (scour) harus mendapatkan perhatian yang lebih serius. Maka perlu diketahui bagaimana kondisi tanah eksisting terhadap erosi atau gerusan, hal tersebut dapat dilakukan dengan pengujian erodibilitas dari Briaud et al. (2017) yang dilakukan pada tanah sesuai klasifikasi USCS untuk membuat grafik kerentanan terhadap erosi sesuai referensi dari Briaud (2008). Berdasarkan kondisi tanah eksisting daerah Kali Lamong dan variasi dimensi pada parameter studi ini diketahui bahwa pondasi tanah tanggul merupakan faktor paling penting dalam pengaruh kenaikan faktor keamanan sebuah tanggul. Hasil penelitian ini menunjukkan bahwa variasi kondisi tanah yang paling aman/stabil untuk pembangunan tanggul adalah variasi I yaitu dengan tanah material timbunan c = 20 kPa; φ = 35° γ = γwet = 22 KN/m3 dan pondasi c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3, variasi III yaitu dengan tanah material timbunan c = 18 kPa; φ = 30° γ = γwet = 16 KN/m3 dan pondasi c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3 serta variasi V yaitu dengan tanah material timbunan c = 16 kPa; φ = 25° γ = γwet = 14 KN/m3 dan pondasi c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3. Material pondasi dari ketiga variasi tersebut berupa tanah lunak dengan material timbunan bagus, sedang dan buruk, dengan variasi dimensi tinggi tanggul bagian dalam (water-side) 3 m dengan setiap variasi tinggi jagaan. Pada grafik evaluasi dapat diketahui pengaruh parameter kondisi tanah, geometrik, dan muka air terhadap nilai faktor keamanan tanggul eksisting Kali Lamong. Dari grafik evaluasi stabilitas tanggul eksisting Kali Lamong diketahui bahwa pada setiap parameter variasi kondisi tanah untuk sisi tanggul bagian dalam (water-side) mengalami kenaikan nilai faktor keamanan ketika tinggi tanggul bagian dalam (water-side) bertambah, sedangkan untuk sisi tanggul bagian luar (land- side) mengalami penurunan nilai faktor keamanan ketika tinggi tanggul bagian dalam (water- side) bertambah. Gerusan yang terjadi pada tanah eksisting kawasan Kali Lamong yang telah diuji pada Laboratorium Tanah Jurusan Teknik Pengairan menurut klasifikasi USCS bahwa tanah jenis CH masuk ke dalam kategori erodibilitas II – III (high until medium erodibillity) dan MH memasukki kategori erodibilitas III – IV (medium until low erodibility) sesuai dengan grafik Briaud (2008).
English Abstract
Lamong river has a watershed area around 720 km2 that is located in East Java Province. The use of border river area as residential area in Lamong river is one of the reason flood always been an issues for years, regarding to ministerial regulation of PUPR No. 28/PRT/M/2015, minimum distance of border area for river that has levee in urban area is 5 meter from the outer foot of the levee along the river channel. The impact of flood caused by overflowing Kali Lamong affected people living along the riverbanks every year, also submerged a lot of rice fields, roads, and schools. This concluded that building a qualified levee is one of the crucial solutions to solve flood issues in Lamong river in order to avoid more severe and widespread flooding. In extreme flood conditions with strong river flows, the collapse of the levee due to erosion or scour should receive more serious attention. So it is necessary to know how the existing soil conditions against erosion or scour, this can be done by testing the erodibility of Briaud et al. (2017) which was carried out on soil according to the USCS classification to create a graph of vulnerability to erosion according to the reference from Briaud (2008). Based on the existing soil condition in the Lamong river area and parameters of dimensional variation in this study, it is known that the levee foundation is the most important factor in the effect of increasing the safety factor number of the levee. The results of this study indicate that the variation of the safest/stable soil conditions for the construction of the levee are variation I, which the condition of the soil embankment are c = 20 kPa; φ = 35° γ = γwet = 22 KN/m3 and for the foundation soil condition are c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3, variation III which the condition of the soil embankment are c = 18 kPa; φ = 30° γ = γwet = 16 KN/m3 and for the foundation soil condition are c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3 as well as variation V which the condition of the soil embankment are c = 16 kPa; φ = 25° γ = γwet = 14 KN/m3 and for the foundation soil condition are c = 6 kPa; φ = 15° γ = γwet = 16 KN/m3. As seen in the result, the material of the foundation for the three variation are soft soil, and the material of the embankment are good, medium, and bad soil conditions with variation dimensional of the inner levee height (water-side) is 3 m with each variation height of outer levee height (land-side). In the evaluation chart, it can be seen the influence of the parameters of soil, geometric, and water levels on the value of the safety factor of the existing Lamong River levee. As seen as the evaluation chart it is known that for each parameter of the variation in soil conditions for the inner side of levee (water-side), the value of the safety factor increases when the inner side of levee (water-side) height increases while, the outer side of levee (land-side) experienced a decrease in the value of the safety factor when the inner side of levee (water-side) height increased. The scour that occurs in the existing soil in the Lamong river area which has been tested at the Soil Laboratory of the Department of Water Resources Engineering according to the USCS classification, shows that CH enters the erodibility category II – III (high to medium erodibility) and MH enters the erodibility category III – IV (medium to low erodibility) according to the graph of Briaud (2008).
Other obstract
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| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | 0521070285 |
| Uncontrolled Keywords: | Kata kunci: Grafik Evaluasi, Tanggul, Stabilitas |
| Subjects: | 600 Technology (Applied sciences) > 627 Hydraulic engineering > 627.5 Reclamations, Irrigation, related topics > 627.52 Irrigation |
| Divisions: | Fakultas Teknik > Teknik Pengairan |
| Depositing User: | yulia Chasanah |
| Date Deposited: | 01 Mar 2022 06:59 |
| Last Modified: | 01 Mar 2022 08:47 |
| URI: | http://repository.ub.ac.id/id/eprint/189916 |
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