Hapsari, Arlita Mey (2019) Identifikasi Sifat Fisik dan Mineralogi Material Tebing Sungai Kali Putih Kecamatan Garum Kabupaten Blitar. Sarjana thesis, Universitas Brawijaya.
Abstract
Gunung Kelud merupakan salah satu gunung api aktif dengan tipe stratovolcano dengan rentang waktu letusan berkisar 9-25 tahun. Letusan Gunung Kelud didominasi oleh letusan eksplosif yang menghasilkan endapan material piroklastik. Pada letusan Gunung Kelud tahun 2014 saja, sebanyak 120.000.000 m3 material vulkanik. Dengan material yang sangat melimpah, potensi penambangan material semakin besar terlebih untuk material pasir, sehingga rawan terjadinya eksploitasi tak terkendali yang dapat berakibat pada kerusakan lingkungan dan berpotensi bahaya. Selain potensi bahaya dari erupsi Gunung Kelud, banjir kiriman yang berasal dari kawasan hulu hingga terjadinya kelongsoran tebing sungai. Terdapat beberapa kasus kelongsoran tebing sungai antara lain di Sungai Gendol, Sleman, di Sungai Kali Pancing dan di Sungai Kali Putih di Blitar. Berdasarkan masalah yang telah dijelaskan, munculah gagasan untuk melakukan penelitian terkait identifikasi fisik dan mineral dari material lokasi kelongsoran tebing dengan pengujian laboratorium. Dalam penelitian ini menggunakan material asli dari lokasi kelongsoran tebing Sungai Kali Putih yang tersebar pada 4 lokasi dengan masing masing lokasi berjumlah 3 titik dengan penamaan sampel A1, A2, A3, B1, B2, B3, C1, C2, C2, C3, D1, D2, dan D3. Dari 12 sampel yang diperoleh dilakukan uji karakter fisik dan mineralogi. Uji karakteristik fisik dilakukan dengan uji gradasi butiran (sieve analysis), uji berat jenis tanah (specific gravity), kerapatan butiran dan angka pori (relative density and void ratio). Sedangkan untuk menguji karakteristik mikroskopik dan mineralogi dilakukan dengan uji SEM (Scanning Electron Microscope) dan uji X-RD (X-Ray Diffraction). Sistem Klasifikasi yang digunakan terdapat 3 klasifikasi yakni AASHTO, USCS, dan JGS. Berdasarkan uji karkateristik fisik diperoleh hasil untuk uji gradasi butiran (pada sampel A1, A2, A3, B2, B3, C1, D1, dan D3 dengan gradasi butiran baik, sedangkan untuk sampel B1, C2, C3, dan D1 memiliki gradasi sedikit baik. Hasil uji berat jenis tanah didapatkan nilai Gs berkisar antara 2.650-2.697 yang digolongkan dalam jenis kerikil/pasir. Hasil uji kerapatan butiran dan angka diperoleh nilai e min berkisar antara 0.383-0.606 dan nilai e max berkisar antara 0.667-0.882. Klasifikasi menurut USCS, sampel termasuk dalam jenis tanah pasir dengan simbol SW (Sand Well-graded). Hasil klasifikasi AASHTO sampel termasuk dalam tanah berbutir kasar dengan klasifikasi kelompok A-1b. Menurut hasil klasifikasi JGS, sampel dari lokasi termasuk jenis tanah Coarse-grained soil¸untuk sampel A1, A3, B3, C1, dan D3 termasuk dalam pembagian jenis tanah Volcanic Soil, sedangkan untuk sampel A2, B1, B2, C2, C3, D1, dan D2 termasuk dalam Sand Volcanic. Berdasarkan uji identifikasi mikroskopik dan mineralogi, sampel yang diuji adalah A1, B3, C1, C2, dan D1. Sampel A2, C1, C2 dan D1 memiliki rongga-rongga udara pada seluruh permukaan partikel. Hanya B3 yang memiliki sedikit rongga udara. Berdasarkan uji SEM dapat diketahui bahwa butiran sampel termasuk dalam low sphericity dengan rentang kategori butiran dari angular sampai dengan sub angular serta memiliki bentuk butiran bladedoblate. Berdasarkan hasil X-RD diperoleh kandungan senyawa dalam sampel anorthite (Ca(Al2Si2O8)) dan albite (Na(AlSi3O8)). Apabila dikaitkan dengan Reaksi Bowen, senyawa ini banyak ditemukan pada material muda yang proses pelapukannya masih berlangsung.
English Abstract
Mount Kelud is one of volcanic mountain which are stratovulcano’s type. The eruption hold in a range 9 to 25 years. The eruption of Kelud dominated by explosive eruption that result pyroclastic deposit. The pyroclastic deposits from the 2014 eruption release 120 million m3 of vulcanic material. The results of large deposit of volcanic sand materials, it causes the exploitation of uncontrolles sand mines. It will have an impact to potential hazard caused by environment damage and potential danger. Beside of that, the potential danger of the eruption of Kelud are flood from upstream and river bank landslide. There are some cases of river bank landslide, for example on the Kali Pancing River and Kali Putih River in Blitar Regency. Based on the previous condition, it is important to study the identification of physical characteristic and mineralogy site of river bank landslide through laboratory testing. The samples used in this study were collected from 4 location along Kali Putih River. From each location, there are 3 location that called sample A1, A2, A3, B3, C1, C2, C2, C3, D1, D2, and D3. From all of the samples were identification of physical characteristic and mineralogy. Physical characteristic identification through seive analysis, specific gravitytest, realtive density and void ratio. Beside of that to identification mycroscopic characteristic and mineralogy through Scanning Electron Microscope (SEM) and X-Ray Diffraction Test (X-RD). In this study used 3 classifications are American Association of State Highway and Transportastion Officials (AASHTO), Unified Soil Classification System (USCS), and Japanese Geotechnical Society System (JGS). As a result of physical characteristic showed that the gradation sample of A1, A2, A3, B2, B3, C1, D1, and D3 were well-graded composition, but sample of B1, C2, C3, and D1 were slightly well-graded. The Gs Value is in a range 2.650 to 2.697 which can be classified as gravel or sand. The minimum void ratio (emin) values were obtained in a range 0.383 to 0.606 and the maximum void ratio (emax) values were observed in a range from 0.667 to 0.882. From USCS classified, all of samples were determined as sandy soil SW (well-graded sand). According to AASHTO standard the sample can be classified as coarse grained soil (A-1b). Based on JGS standard for volcanic soil, these river bank materials can be classified as Coarse-grained soil, sampel of A1, A3, B3, C1, and D3 as Volcanic Soil but sampel of A2, B1, B2, C2, C3, D1, and D2 as Sand Volcanic. Based on microscopic identification and myneralogy, only sample of A1, B3, C1, C2, and D1 that used. As a result of SEM analysis showed a lot of air cavities at surface of the samples. Only sample of B3 showed less air cavities at surface of the sample. From SEM results that the grain samples had a low sphericity with angular to sub-angular and a bladed-oblate granular form. From X-RD analysis the mineral composition of samples were dominated by anorthite (CaAl2Si2O8) and albite (Na (AlSi3O8)). Associated with Bowen's reaction, these compounds are common in young materials when weathering process is still in progress.
Other obstract
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| Item Type: | Thesis (Sarjana) |
|---|---|
| Identification Number: | 0520070066 |
| Uncontrolled Keywords: | Sifat Fisik, Mineralogi, Tebing Sungai, Penambangan Pasir. , Physical Properties, Mineralogy, Riverbank, Sand Mining. |
| Subjects: | 500 Natural sciences and mathematics > 577 Ecology > 577.6 Aquatic ecology |
| Divisions: | Fakultas Teknik > Teknik Pengairan |
| Depositing User: | Users 31 not found. |
| Date Deposited: | 03 Feb 2021 07:37 |
| Last Modified: | 03 Feb 2021 07:37 |
| URI: | http://repository.ub.ac.id/id/eprint/182271 |
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