Karakteristik Geologi Teknik dan Kestabilan Lereng Jalan Lingkar Timur Jatigede Km 00+00 - 08+890, Kabupaten Sumedang, Jawa Barat
LAILY FIDYA, I Gde Budi Indrawan, S.T., M.Eng., Ph.D.
2019 | Skripsi | S1 TEKNIK GEOLOGIJalan lingkar timur Jatigede dibagun sebagai alternatif akses menuju Wado - Cadas Ngampar - Cijeungjing - Tolengeas, karena jalan utama di bagian barat Jatigede rentan terendam banjir pada musim hujan. Pada tahun 2017 telah dilakukan review desain oleh Satker P2JN dan penyelidikan lapangan, akan tetapi evaluasi kondisi geologi teknik belum dilakukan secara menyeluruh. Oleh karena itu dilakukan penyelidikan kondisi geologi teknik meliputi kondisi geomorfologi, persebaran litologi, struktur geologi, kedalaman muka air tanah di daerah penelitian, serta pemodelan kondisi kestabilan lereng. Metode penelitian dilakukan dengan pemetaan geologi teknik skala 1:25.000 dan analisis kestabilan lereng dengan metode kesetimbangan batas (metode simplified Bishop dan Morgenstern-Price). Dalam pembuatan peta geologi teknik, dilakukan klasifikasi massa batuan menggunakan Geological Stength Index (GSI), pengamatan tingkat pelapukan batuan, serta pengujian sifat keteknikan batuan dan tanah. Daerah penelitian termasuk ke dalam bentang alam struktural dengan morfologi yang dikontrol oleh struktur lipatan dan sesar. Karakteristik geologi teknik berdasarkan nilai GSI menunjukkan bahwa batuan di daerah penelitian memiliki kualitas sangat baik, baik, sedang, buruk dan sangat buruk. Karakteristik geologi teknik berdasarkan tingkat pelapukan tersusun atas 9 satuan yaitu satuan batupasir-batulempung lapuk sedang, batupasir-batulempung lapuk sempurna, breksi andesit lapuk rendah, breksi andesit lapuk tinggi, breksi andesit lapuk sempurna, batuserpih lapuk sedang, batuserpih lapuk sempurna, batupasir lapuk sedang, dan batupasir lapuk sempurna. Kestabilan lereng pada daerah penelitian adalah stabil, ditunjukkan oleh faktor keamanan yang bernilai lebih dari 1,5.
The construction of Jatigede east ring road is done as an alternative path to access Wado - Cadas Ngampar - Cijeungjing - Tolengeas which the previous one and only path is prone to flood during the rainy season. In 2017 Satker P2JN had reviewed the design and had done some field investigations, but have not evaluated the engineering geology condition. Therefore, an evaluation of engineering geology condition of geomorphology condition, distribution of lithology, geological structures, groundwater level of the field and slope stability modelling is done. Research is carried out by doing an engineering geology mapping with a scale of 1:25.000 and analysing slope stability with limit equilibrium method (simplified Bishop and Morgenstern-Price method). Engineering geology map is made using Geological Strength Index classification of rock mass data, rocks weathering degree observation data, and also index properties of rocks and soil that have been analysed. The study area is classified as structural landform with morphology controlled by geological structures which are fold and faults. The characteristic of engineering geology in the study area based on Geological Strength Index value can be divided into 5 units, there are rocks which are very good, good, moderate, poor and very poor. Based on rocks weathering degree, the characteristic of engineering geology in the study area consists of 9 units, which are moderately weathered sandstone-claystone, completely weathered sandstone-claystone, slightly weathered andesite breccia, highly weathered andesite breccia, completely weathered andesite breccia, moderately weathered shale, completely weathered shale, moderately weathered sandstone, and completely weathered sandstone. The slope stability condition in the study area is stable which is shown by safety factors of modelled slopes value higher than 1,5.
Kata Kunci : Jalan lingkar timur Jatigede, karakteristik geologi teknik, Geological Stength Index, tingkat pelapukan batuan, kestabilan lereng, faktor keamanan
