ANALISIS KESTABILAN LERENG BATU DI JALAN RAYA LHOKNGA KM 17,8 KABUPATEN ACEH BESAR

Ibnu Rusydy; Nafisah Al-Huda; Khaizal Jamaluddin; Devi Sundary; Gartika Setiya Nugraha

doi:10.14203/risetgeotam2017.v27.452

ANALISIS KESTABILAN LERENG BATU DI JALAN RAYA LHOKNGA KM 17,8 KABUPATEN ACEH BESAR

Ibnu Rusydy, Nafisah Al-Huda, Khaizal Jamaluddin, Devi Sundary, Gartika Setiya Nugraha

Abstract

Penelitian kestabilan lereng batuan menggunakan metode analisis kinematik lereng dan klasifikasi massa batuan dilakukan di lereng pinggir jalan Banda Aceh – Calang di Km 17,8 di Kecamatan Lhoknga Kabupaten Aceh Besar. Penelitian ini bertujuan untuk mengetahui jenis longsoran yang akan terjadi di masa yang akan datang, menilai kualitas massa batuan pembentuk lereng, dan tingkat kestabilannya berdasarkan klasifikasi SMR. Akuisisi data struktur massa batuan dilakukan di sepanjang lereng menggunakan metode scanline. Data yang diambil berupa arah kemiringan bidang diskontinuitas, arah bidang, dan kondisi bidang diskontinuitas bidang berupa kemenerusan, kekasaran, bukaan, isian, luahan air dan tingkat perlapukan. Analisis kinematik lereng didapatkan berdasarkan hasil proyeksi stereografi dan analisis kualitas serta kestabilan lereng batuan berdasarkan parameter RMR dan SMR. Hasil analisis kinematik lereng menunjukkan jenis longsoran yang akan terjadi di lereng 1 berupa longsoran baji dan planar. Di lereng 2 dimungkinkan terjadinya longsoran gulingan/toppling karena bidang joint set yang berlawanan dengan arah lereng. Nilai RMR di lereng 1 sebesar 63 dengan kategori batuan Bagus dan RMR lereng 2 sebesar 57 kategori batuan sedang. Nilai SMR terendah di lereng 1 sebesar 29 (kategori Buruk) untuk longsoran planar dan 53 (kategori Sedang) di lereng 2 longsoran gulingan. Lereng 1 memiliki probabilitas kejadian longsor planar sebesar 60%.

Rock slope stability was assessed using the slope kinematic analysis method and rock mass classification on the roadside slope of Banda Aceh - Calang at 17.8 Km in Lhoknga Sub-district, Aceh Besar District. This study aims to determine the types of landslides that will occur in the future by determining the Rock Mass Rating (RMR) and analyzing stability based on the Slope Mass Rating (SMR). The data acquisition of rock mass structures performed the scan line method along the slope. The data taken are the dip and the strike of the discontinuity plane, and the conditions of discontinuity in the form of persistence, aperture, roughness, infilling, weathering and Groundwater conditions. Slope kinematic analysis was conducted based on stereographic projection and analyses of both rock slope quality and stability were based on RMR and SMR parameters. The result of the slope kinematic analysis shows that landslides that occur in slope 1 will be in wedge and planar forms. On slope 2, possible failure is in the form of toppling due to the joint set positioned opposite to the slope direction. The RMR value in slope 1 is 63, categorized as Good rock and the RMR in slope 2 is 57, which is in the medium rock category. The lowest SMR value in slope 1 was 29 as a Bad class for planar failure, and 53 as a Normal category in slope 2 is toppling failure. Slope 1 has a 60 % probability of a planar failure event.

Keywords

slope stability, kinematic analysis, rock mass classification

Full Text:

PDF (Bahasa Indonesia)

References

Barber, A. J., 2000. The Origin Of The Woyla Terranes In Sumatra And The Late Mesozoic Evolution Of The Sundaland Margin. Journal of Asian Earth Sciences, 18(6), 713-738.

DOI: 10.1016/S1367-9120(00)00024-9

Barber, A. J., dan Crow, M. J., 2005. Pre-Tertiary stratigraphy. dalam: A. J. Barber, M. J. Crow & J. S. Milson. Sumatra: Geology, Resources, and Tectonic Evolution. London: Geological Society, 40 pp.

DOI: https://doi.org/10.1144/GSL.MEM.2005.031

Barton, N. R., Lien, R., dan Lunde, J., 1974. Engineering classification of rock masses for the design of tunnel support. Rock Mech, 6(4), 189-239. DOI: 10.1007/BF01239496.

Bieniawski, Z. T., 1989. Engineering Rock Mass Classification. New York: John Wiley & Sons.

Bridge, D. M., Bennet, J. D., Cameron, N. R., 1981. Peta Geologi Lembar Banda Aceh, Sumatra, Lembar G-421, Skala 1:250000. Pusat Survey Geologi, Indonesia.

Brown, E. T., 1981. Rock Characterization, Testing and Monitoring, ISRM Suggested Methods. Oxford: Published for the Commission on Testing Methods, International Society for Rock Mechanics by Pergamon Press.

Deere, D. U., Hendron, A. J., Patton, F. D., dan Cording, E. J., 1967. Design of Surface and Near-Surface Construction in Rock. dalam: C. Fairhurst. Failure and Breakage of Rock. New York: Society of Mining Engineers of ALME, 237-302.

Goodman, R. E., 1989. Introduction to Rock Mechanics. 2nd. New York: Wiley.

Grelle, G., Revellino, P., Donnarumma, A. dan Guadagno, F. M., 2011. Bedding control on landslides: a methodological approach for computer-aided mapping analysis. Nat. Hazards Earth Syst. Sci, V(11), 1395–1409. DOI:10.5194/nhess-11-1395-2011

Gurocak, Z., Alemdag, S. dan Zaman, M. M., 2008. Rock slope stability and excavatability assessment of rocks at the Kapikaya dam site, Turkey. Engineering Geology, 96, 17-27.

DOI: 10.1016/j.enggeo.2007.08.005

Hoek, E., 2007. Practical Rock Engineering. 1st. Canada: Rock Science.

Hoek, E., dan Bray, J. W., 1981. Rock Slope Engineering. 3rd. London: Institute of Mining and Metallurgy.

Lee, C.-Y., dan Wang, I.-T., 2011. Analysis of Highway Slope Failure by an Application of the Stereographic Projection. Taiwan, World Academy of Science, Engineering and Technology.

Priest, S. D., 1993. Discontinuity Analysis for Rock Engineering. London: Chapman and Hall.

Rai, M. A., Kramadibrata, S. dan Wattimena, R. K., 2014. Mekanika Batuan. Bandung: Penerbit ITB.

Romana, M., 1985. New Adjustment Ratings for Application of Bieniawski Classification to Slope. Mexico, ISRM, 59-68.

Rusydy, I., Sugiyanto, D., Satrio, L., Zulfahriza, Rahman, A., Munandar, I., 2016. Geological Aspect of Slope Failure and Mitigation Approach in Bireun-Takengon Main Road, Aceh Province, Indonesia. Aceh International Journal of Science and Technology, 5(1), 30-37. DOI: 10.13170/aijst.5.1.3841

Vollmer, F. W., 1995. C program for automatic contouring of spherical orientation data using a modified Kamb method. Computers & Geosciences, 21, 31-49.

DOI: 10.1016/0098-3004(94)00058-3

Vollmer, F. W., 2017. Orient: Spherical projection and orientation data analysis software. [Online] Available at: http://www.frederickvollmer.com/ orient/ [Diakses 26 March 2017].

Wyllie, D. C., dan Mah, C. W., 2004. Rock Slope Engineering (Civil and Mining). 4th ed. Spon Press, London and New York.

DOI: http://dx.doi.org/10.14203/risetgeotam2017.v27.452