ANALISIS KEKUATAN MASSA BATUAN ANDESIT MENGGUNAKAN KAIDAH KRITERIA KERUNTUHAN HOEK-BROWN UNTUK MENGETAHUI NILAI FAKTOR KEAMANAN LERENG PADA DAERAH SELOHARJO, KECAMATAN PUNDONG, KABUPATEN BANTUL, DIY
DOI:
https://doi.org/10.34151/technoscientia.v11i1.110Keywords:
andesite, Hoek-Brown collapse, safety factor, slopeAbstract
The study area has a steep hill morphology with dominant lithology of andesite lava from the Ngelanggran Formation. Steep morphology with water saturated conditions and platy joints on andesite lava as rock discontinuities with different properties and weathering can be weaking the slope stability. Analysis of the rock mass strength of andesite lava with Hoek-Brown collapse criteria using GSI, mi, uniaxial compressive strength, and D values can be used to obtain rock strength in the form of cohesion (c) and internal friction angle (ɸ), to be applied in the analysis of slope stability. The safety factor (FS) on the slope concists lithology and platy joints and massive using the equilibrium limits approach on the natural slopes shows on safe conditions (FK = 7.5). On very steep slope (slope angle 80o) in LP S09B location which is the former slope of mining activity with lithology andesit platy jointings have strong slopes, and in the field of rock mass movement shows the result of FK value = 1.3 which is below the PU standard (> 1.5). Slope reinforcement can be done by lowering slope angle up to 75o so that the safe conditions at FS = 2.4.
References
Bieniawski, Z. T., 1989, Engineering Rock Mass Classifications, New York: John Wiley & Sons.
Bemmelen, R. W., 1949, The Geology of Indonesia, Vol. IA, Netherland: The Haque Martinus Nijhroff, Government Printing Office.
Goodman, R. E., 1976, Introduction to Rock Mechanics, 2nd ed., Singapore: John Wiley & Sons.
Hoek, E., Torres, C., and Corkum, B., 2002, Hoek-Brown Failure Criterion, Rockscience Inc., Toronto, Canada.
Hoek, E., 2007, Practical Rock Engineering, Notes, Evert Hoek Consulting Engineer Inc., Canada.
Sonmez, H. and Ulusay, R,. 1999, Modifications to Geological Strength Index (GSI) and Their Applicability to Stability of Slopes, Int. J. Rock Mech. Min. Sci., Vol. 36.
MacDonald, G. A., 1972, Volcanoes, New Jersey: Prentice-Hall, Englewood Cliffs.
Rahardjo, W., Sukandarrumidi, dan Rosidi H. M. D., 1995, Peta Geologi Lembar Yogyakarta, Jawa, Skala 1 : 100.000, Pusat Penelitian dan Pengembangan Geologi.
Williams, H., Turner, F. J., dan Gilbert, C. M., 1954, Petrography, An Introduction to The Study of Rock in Thin Sections, W. H. Freeman and Company, New York.
Van Bemmelen, R. W., 1949, The Geology of Indonesia, Vol. IA, General Geology of Indonesia And Adjacent Archipelagoes, 2nd ed., Martinus Nijhoff, The Hague.
Van Zuidam, R. A., 1983, Guide to Geomorfhology Ariel Photographic Interpretation and Mapping, ITC Enschede The Nederland.
