ANALISIS POTENSI LONGSOR MENGGUNAKAN DATA GROUND PENETRATING RADAR (GPR) DAN DATA MEKANIKA TANAH DI KAMPUNG CIBITUNG KECAMATAN PANGALENGAN KABUPATEN BANDUNG - Agustina Dwi Puspitasari, - (2023)
Kampung Cibitung, Kecamatan Pangalengan, Kabupaten Bandung merupakan salah satu kawasan di Jawa Barat yang memiliki kerentanan longsor yang cukup tinggi, untuk mengetahui potensi longsor, maka dilakukannya analisis kestabilan lereng. Melalui survei metode Ground Penetrating Radar (GPR) dan pengambilan sampel tanah telah dilakukan di kampung Cibitung, Kecamatan Pangalengan, Kabupaten Bandung. Pengambilan data GPR diambil sebanyak 2 lintasan dari arah barat ke timur, dengan menggunakan alat GSSI SIR 3000, serta antena shieldied dan frekuensi 100 MHz dengan metode akuisisi pengambilan data radar refection profiling. Sedangkan sampel tanah diambil sebanyak 4 titik untuk pengujian mekanika tanah. Dari kedua data tersebut dilakukan pemodelan menggunakan metode kesetimbangan batas umum dengan software Geostudio dan pyBIMstab dalam keadaan eksisting (natural condition) sehingga diketahui kestabilan lereng. Dan juga menerapkan keadaan kritis lereng untuk menganalisis potensi longsor, sehingga dapat mengetahui prediksi kecepatan dan jarak jangkauan longsor dengan pendekatan pusat massa dan model gesekan Coulomb sederhana. Dari analisis menggunakan metode tersebut diperoleh pada keadaaan eksisting, lereng dalam keadaan stabil, sehingga tidak berpotensi longsor. Sedangkan dalam keadaan kritis memperoleh bidang gelincir sepanjang 38,34 - 45,4 meter, dengan kedalaman 1 - 5 meter, yang dikategorikan sebagai longsor dangkal dengan tipe longsoran translasi dan rotasi. Untuk jarak jangkauan diperoleh 37,95 - 61,72 meter dengan kecepatan 4,40 - 4,91 meter, sehingga termasuk kategori kecepatan yang ekstrim sangat cepat. Dari hasil tersebut diharapkan dapat adanya rambu - rambu daerah rawan longsor, sehingga dapat meningkatkan kewaspadaan bagi warga yang beraktivitas di area tersebut dan para pekerja di PT. Star Energy Geothermal (Wayang Windu). Cibitung village, Pangalengan District, Bandung Regency is one of the areas in West Java that is highly susceptible to landslides. To assess the landslide potential, a slope stability analysis was conducted. Ground Penetrating Radar (GPR) survey and soil sampling were performed in Kampung Cibitung, Pangalengan District, Bandung Regency. Two GPR profiles were collected from west to east using a GSSI SIR 3000 instrument with a shielded antenna operating at a frequency of 100 MHz. The data acquisition method employed was radar reflection profiling. Additionally, four soil samples were taken for geotechnical testing. The collected data was then used for modelling using the limit equilibrium method with software such as Geostudio and pyBIMstab, under existing (natural conditions), to determine slope stability. Furthermore, the critical slope conditions were applied to analyse the landslide potential, predicting the velocity and run-out of the landslide using the center of mass approach and the simple Coulomb friction model. Based on the analysis using these methods, it was determined that the slope is stable under existing conditions, indicating no potential for landslides. However, under critical conditions, a potential sliding surface with a length ranging from 38.34 to 45.4 meters and a depth of 1 to 5 meters was identified. This type of landslide is categorized as shallow translational and rotational landslides. The predicted run-out was found to be between 37.95 to 61.72 meters, with velocities ranging from 4.40 to 4.91 meters, indicating an extremely fast speed. Based on these findings, it is recommended to establish warning signs in landslide-prone areas to increase awareness among residents and workers at PT. Star Energy Geothermal (Wayang Windu) who are active in the area.