Aplikasi Metode Penyelidikan Tanah Non

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