LAPORAN AKHIR TAHUN 1 PENELITIAN UNGGULAN PERGURUAN TINGGI
JUDUL APLIKASI METODE PENYELIDIKAN TANAH NON-DESTRUCTIVE PADA LERENG TANAH KRITIS UNTUK PENYUSUNAN PETA KERAWANAN BENCANA TANAH LONGSOR DI RUAS JALAN BATU-PUJON
Tahun ke-1 dari rencana 2 tahun Tim Peneliti Ketua : Eko Andi Suryo, ST., MT., Ph.D (NIDN: 0023107606) Anggota 1 : Dr. rer. nat. Ir. Arief Rachmansyah (NIDN: 0020046606) Anggota 2 : Dr. Eng. Indradi Wijatmiko, ST., MEng. (Prac) (NIDN: 0020028104) Dibiayai oleh : Direktorat Jenderal Pendidikan Tinggi, Kementerian Pendidikan dan Kebudayaan, Melalui DIPA Universitas Brawijaya Nomor : 023.04.2.414989/2014, Tanggal 5 Desember 2013, dan berdasarkan SK Rektor Universitas Brawijaya Nomor 157 Tahun 2014 tanggal 10 April 2014
UNIVERSITAS BRAWIJAYA NOVEMBER 2014
RINGKASAN
Judul: Aplikasi Metode Penyelidikan Tanah Non-Destructive pada Lereng Kritis dalam rangka Penyusunan Peta Kerawanan Bencana Tanah Longsor di Ruas Jalan Batu – Pujon Metode yang umum digunakan di jalan sepanjang lereng gunung adalah cutting slope yang berpotensi menurunkan tingkat kestabilan lereng gunung tersebut. Penyelidikan terhadap safety factor dari lereng tersebut terutama saat musim penghujan menjadi hal yang penting bagi keselematan pengguna jalan. Hal utama yang harus diperhatikan dalam penyelidikan tanah di lapang adalah kondisi hazard yang dapat mengancam jiwa operator pengeboran akibat kondisi lereng kritis yang sangat tidak stabil. Oleh karena itu perlu dicari metode yang lebih aman (tidak langsung dan tidak merusak) sebagai pengganti metode pengeboran langsung (bore-hole wash drilling) yang selanjutnya dapat diaplikasikan dalam penyusunan Peta Kerawanan Bencana Longsor. Untuk menyusun metode alternatif tersebut, dilakukan penelitian dengan mengaplikasikan metode Geofisika (Electrical Resistivity Tomography- ERT dan Ground Penetration Radar – GPR) yang diverifikasi dengan data parameter tanah sehingga lapisan tanah di lereng kritis tersebut dapat diinterpretasikan. Dalam studi awal, verifikasi ini dilakukan secara langsung (dengan model lereng di laboratorium) dan secara tak langsung (dengan urugan Dam Selorejo). Dari rumusan hubungan antara hasil ERT/GPR dengan data tanah ini, selanjutnya ERT/GPR diaplikasikan di lereng kritis di ruas jalan Pujon dan diverifikasi secara tidak langsung dengan menggunakan data tanah hasil bore-hole wash drilling di lokasi aman untuk mendapatkan panduan interpretasi lapisan tanah untuk model lereng kritis. Selanjutnya, model lereng kritis tersebut dipakai dalam analisa numeric stabilitas lereng. Dari hasil analisa numeric tersebut dapat dikembangkan dalam bentuk peta kerawanan bencana longsor di sepanjang ruas jalan pegunungan Pujon dengan cara mengaplikasikan ERT atau GPR di 5 lokasi lereng kritis serta melakukan pemetaan digital dengan aplikasi GIS. Hasil dari penelitian ini diharapkan dapat dipakai sebagai alternative metode non-destructive field soil investigation menggunakan ERT/GPR yang bila dipadukan dengan hasil analisa stabilitas di beberapa lokasi lereng kritis dan teknologi GIS maka dapat disusun Peta Kerawanan Bencana Tanah Longsor di ruas jalan tersebut. Keywords: Longsor, ERT, GPR, Lereng Kritis, Safety Factor, Peta Kerawanan Bencana.
DAFTAR PUSTAKA Baker, R.(1981). Tensile Strength, Tension Cracks, and Stability of Slopes. Japanese Society of Soil Mechanics and Foundation Engineering, 21(2), 17. Benson, A.K. (1995). Applications of Ground Penetrating Radar in assessing some Geological Hazards: Examples of Groundwater Contamination, Faults, Cavities. Journal of Applied Geophysics, 33, 177-193 BPS Jatim. (2012). Geografi Jawa Timur. Retrieved April 2013 at http://jatim.bps.go.id/index.php/tentang-daerah/keadaan-geografi-jatim Brand, E.W. (1984). Landslides in southeast Asia: a state-of-the-art report. In Proceedings of the 4th International Symposium on Landslides, Toronto, Canada, 1984. 1, 17 - 59. Brand, E.W. (1996). Keynote Paper: Slope Instability in Tropical Areas. Proc. Of 7th International Symposium on Landslides, Trondheim, 2031 – 2051. Brand, E.W., Premchitt, J. & Phillipson, H.B. (1984). Relationship between Rainfall and Landslides in Hong Kong. In Proceedings of the 4th International Symposium on Landslides, Toronto, Canada 1, 377 - 384. Busby, J. & Jackson, P. (2006). The Application of Time-lapse Azimuthal Apparent Resistivity Measurement for the Prediction of Coastal Cliff Failure. Journal of Applied Geophysics, 59, 261 – 272. Chipp, P.N., Henkel, D.J., Clare, D.G., & Pope, R.G. (1982). Field measurement of suction in colluvium covered slopes in Hong Kong. In Proceedings of the Seventh Southeast Asian Geotechnical Conference, November 22-26 Hong Kong: 49-62. Chowdhury, R.N. & Zhang, S (1991). Tension Cracks and Slope Failure. Slope Stability Engineering, Proc. International Conference, Isle of Wright, 27-32. Chowdhury, R., Flentje, P., & Bhattacharya, G. (2010). Geotechnical Slope Analysis. Taylor & Francis Group. London. Craig, R.F. (2004). Craig’s Soil Mechanics (7th edition). London: Spon Press.. Fredlund, D.G. & Rahardjo, H. (1993). Soil Mechanics for Unsaturated Soils. New York: John Wiley & Sons, Inc. Friedel, S., Thielen, A. & Springman, S.M. (2006). Investigation of a Slope Endangered by Rainfallinduced Landslides using 3D Resistivity Tomography and Geotechnical Testing. Journal of Applied Geophysics, 60, 100 – 114. Geo-slope International Ltd. (2010). Stability Modeling with SLOPE/W 2007 version (4th Ed.). Calgary, Alberta, Canada. Gori, P.L. & Hays. (1987). Earthquake Hazards Along the Wasatch Front, Utah. US Geological Survey, 87-154. Gori, P.L. & Hays. (1988) Assessment of Regional Earthquake Hazards and Risk Along the Wasatch Front, Utah, III. US Geological Survey, 88-680. Hunaidi, O. & Giamou, P. (1998). Ground-penetrating Radar for Detection of Leaks in Buried Plastic water Distribution Pipes. Paper presented at Seventh International Conference on Ground Penetrating Radar, USA, 783. Johnson, K.A. & Sitar, N. (1990). Hydrologic conditions leading to debris-flow initiation. Canadian Geotechnical Journal, 27, 789 - 801 Khattak, G.A., Owen, L.A.,Kamp, U., & Harp, E.L. (2009). Evolution of Earthquake-Triggered Landslides in the Kashmir Himalaya, Northern Pakistan. Geomorphology, 115, 102 – 108. Lavigne, F. & Suwa, H. (2004). Contrasts between debris flows, hyperconcentrated flows and stream flows at a channel of Mount Semeru, East Java, Indonesia. Geomorphology, 61, 41-58. Lee, F.H., Lo, K.W., & Lee, S.L. (1988). Tension Crack Development in Soils. Journal of Geotechnical Enineering, 114(8): 915-929.
Li, J. (2009). Field Experimental Study and Numerical Simulation of Seepage in Saturated/Unsaturated Cracked Soil. PhD Thesis. The Hong Kong University of Science and Technology. Hong Kong.. Lim, T.T., Rahardjo, H., Chang, M.F. & Fredlund, D.G. (1996). Effect of Rainfall on Matric Suction in a Residual Soil Slope. Canadian Geotechnical Journal, 33(2), 618 – 628. Milsom, J. (2003). Field Geophysics. England: John Wiley and Sons Ltd. Ng, C.W.W. & Shi, Q (1998). A Numerical Investigation of the Stability of Unsaturated Soil Slopes Subjected to Transient Seepage. Computer and Geotechnics, 22 (1), 1 – 28 NGA (2000). D.C. Resistivity. Retrieved August 23rd, 2010, from http://www.nga.com/Flyers_PDF/NGA_DC_Resistivity.pdf Oh, A. & Sun, C. (2008). Combined Analysis of Electrical Resistivity and Geotechnical SPT blow Counts for the Safety Assessment of Fill Dam. Environ Geol, 54, 31 -42. Owen, L.A., Kamp, U., Khattak, G.A., Harp, E.L., Keefer D.K., & Bauer, M.A. (2008). Landslide Triggered by the 8 October 2005 Kashmir Eartquake. Geomorphology, 94, 1 – 9. Pitts, J. (1983). The Form and Causes of Slope Failures in an Area of West Singapore Island. Singapore Journal of Tropical Geography 4(2), 162 - 8. Pitts, J. (1985). An investigation of slope stability on the NTI campus, Singapore. Nanyang Technological Institute, Applied Research Project, March, 1985. Samouelian, A., Cousin, I., Richard, G., Tabbagh, A. & Bruand, A. (2003). Electrical Resistivity Imaging for Detecting Soil Cracking at the Centimetric Scale. Soil Science Society of America Journal, 67(5), 13-19. Sato, H.P., Hasegawa, H., Fujiwara, S., Tobita, M., Koarai, M., Une, H., & Iwahashi, J. (2007). Interpretation of landslide Distribution Triggered by the 2005 northern Pakistan Earthquake using SPOT 5 Imagery. Landslide, 4, 113 – 122. Schmutz, M., Andrieux, P., Bobachev, A., Montoroi, J.P. & Nasri, S. (2006). Azimuthal Resistivity Sounding over a Steeply Dipping Anisotropic Formation: A Case History in Central Tunisia. Journal of Applied Geophysics, 60, 213 – 224. Senos-Matias, M.J. (2002). Square Array Anisotropy Measurement and Resistivity Sounding Interpretation. Journal of Applied Geophysics, 49, 185 – 194. Sudha, K., Israil, M., Mittal, S. & Rai, J. (2009). Soil Characterization using Electrical Resistivity Tomography and Geotechnical Investigations. Journal of Applied Geophysics, 67, 74 – 79. Suryo, E.A., Gallage, C., Trigunarsyah, B., Mochtar, I.B. and Soemitro, R.A.A. (2011) Application of electrical resistivity method to detect deep crack in unsaturated residual soil slope. Proc., 5th Asia-Pacisif Conf. on Unsaturated Soils (AP-UNSAT 2011), Kasetsart University, Pattaya, Thailand, 901-906. Sweeney DJ & Robertson PK. (1979). A Fundamental Approach to Slope Stability problems in Hong Kong. Hong Kong, 35-44. Syahbuddin, H., & Wihendar, T.N. (2010). Anomali Curah Hujan Periode 2010 – 2040 di Indonesia. Retrieved August 2, 2010. From http://balitklimat.litbang.deptan.go.id. Tabbagh, J., Samouelian, A., Tabbagh, A. & Cousin, I. (2007). Numerical Modelling of Direct Current Electrical Resistivity for the Characterisation of Cracks in Soils. Journal of Applied Geophysics, 62, 313 – 323. Tan, S.B., Lim, T.L., Tan, S.L., & Yang, K.S. (1987). Landslide Problems and their Control in Singapore. In: 9th Southeast Asian Geotechnical Conference, Bangkok, Thailand. USGS (n.d.). Seismotectonics of the Indonesian Region. Retrieved August 11st , 2010, from http://earthquake.usgs.gov/earthquakes/world/indonesia/seismotectonics.php
Yao, H.L., Zheng, S.H., & Chen, S.Y. (2001). Analysis of the Slope Stability of Expansive Soil considering Cracks and Infiltration of Rainwater. Chinese Journal of Geotechnical Engineering, 23(5): 606-609. Zhu, T., Feng, R., Hao, J., Zhou, J., Wang, H., Wang, S. (2009). The Application of Electrical Resistivity Tomography to Detecting a Buried Fault: A Case Study. JEEG, 14(3), 145 – 151
