An example for preparation of probabilistic risk map of wedge type failures: Altındağ (Ankara)

Öz

The evaluation of potential rock slope failures using stereographic projection techniques known as kinematic analysis is one of the most important parts of a slope stability investigation to be carried out in in jointed rock media. In conventional stereo projection techniques for the assessment of possible rock slope failures, the peak orientations of joints together with the slope geometry and the friction angle of the weakness planes are used. Other possible joint orientations which may be encountered in the rock media are ignored. In the present study, possible wedge failures which can develop in jointed andesites cropped out Ankara and its vicinity were investigated using both conventional and probabilistic kinematic analysis methods, and risk maps were produced using the results obtained from kinematic analysis and a comparison was made between the results. According to the results obtained from this study, probabilistic risk map are more realistic than the map using conventional kinematic analysis, because, all the actual wedge type slope failures developed in the study area are located on the risk zones of the probabilistic risk map. When three peak orientations of the discontinuities are used for the preparation of the risk map, 20% of the study shows wedge type failure risk. However, this value goes up to 73% when the probabilistic kinematic analysis is applied. In conclusion, each possible discontinuity orientation must be taken into consideration in a kinematic analysis research program. This phenomenon is important for the selection and planning of settlement regions particularly, because, a failure can cause important hazards and loss of life. Besides, the procedure described in the present study is very simple.

Anahtar Kelimeler

• Altındağ (Ankara)
• andesite
• kinematic analysis
• probabilistic analysis
• risk map

Kama türü yenilmelerin olasılıklı risk haritasının hazırlanmasına bir örnek: Altındağ (Ankara)

Öz

Eklemli kaya kütleleri içerisinde yapılan şev duraylılığı araştırmalarının en önemli aşamalarından birisini stereografik projeksiyon tekniklerini kullanarak gerçekleştirilen kinematik analizler oluşturur. Klasik yöntemler kullanılarak kaya şevlerinin olası yenilmelerinin incelenmesinde, eklem yönelimlerinin en yoğun olduğu konumun yanı sıra şev geometrisi ve zayıflık düzleminin sürtünme açısı parametre olarak kullanılır. Bu durumda merkezde yoğunlaşmayan ancak şevin duraysızlığını kontrol edebilecek diğer konumlar gözardı edilir. Bu çalışmada Ankara ve civarında yüzeylenen eklemli andezit kütlesi içerisinde gelişebilecek olası kama türü yenilmelerin analizi hem klasik kinematik analiz hem de olasılıklı kinematik analiz yöntemleriyle araştırılmış ve elde edilen sonuçlar kullanılarak risk haritaları üretilmiş ve bir karşılaştırma yapılmıştır.

Anahtar Kelimeler

• Altındağ (Ankara)
• andezit
• kinematik analiz
• olasılık analizi
• risk haritası.

Kaynakça

1. Baecher, G.B., ve Einstein, H.H., 1978. Slope stability models in pit optimisation. International Proceedings 16 Apcom Sysmp., Tucson, AZ, U.S.A., 501-512.
2. Barton, M.R., 1973. Review of a new shear strength criterion for rock joints, Engineering Geology, 7, 287-332.
3. Carosso, G., DelGreco, O., ve Giani, G.P., 1987. Some probabilistic approaches to stability analysis of open pit explorations. In Proceedings of International Symposium on Engineering Geology, Beijing, China, 881-891.
4. Chiao, L.Y., 1985. Fortran-V program for contorting point density on PI diagrams using a microcomputer. Computer and Geosciences, 11 (5) 647-657.
5. Chowdhury, R.N., 1986. Geomechanics risk model for multiple failures along rock discontinuities. International Journal of Rock Mechanics Mining Science and Geomechanics Abstracts, 23 (5) 337-346.
6. Chowdhury, R.N., 1987. Risk of slip along discontinuities in a heterogenous medium. Mining Science and Technology, 4, 241-255.
7. Diederich, M.S., Hoek, E., 1989. DIPS, A computer program for stereographic net, (Version 2.2, Advanced Version). Rock Engineering Group, Department of Civil Engineering, University of Toronto.
8. D.M.İ., (Devlet Meteoroloji İşleri) 1997. Çubuk istasyonu sıcaklık ve yağış verileri, Ankara.

9. Eastman, J.R., 1992. IDRISI: A grid-based geographic analyses system, User’s guide (Ver. 4.1), Clark University, Massachusetts, 178 p.
10. Einstein, H.H., Baecher, G.B., 1983. Probabilistic and statistical methods in engineering geology, specific methods and examples, Rock Mechanics and Rock Engineering, 16, 39-72.
11. Ercanoğlu. M..,1997. Altındağ (Ankara) yerleşim bölgesindeki andezitlerde olası şev duraysızlık modellerinin incelenmesi ve duraysızlık risk haritasının oluşturulması, Hacettepe Üniversitesi Fen Bilimleri Enstitüsü. Ankara. Yüksek Mühendislik Tezi, 83 s (yayımlanmamış).
12. Ercnlöz, C., 1975. 1/15000 ölçekli Türkiye Jeoloji Haritası. Ankara Bölgesi. MTA Yayınları, 1 1 1 s.
13. Erol. O., 1961. Ankara bölgesinin tektonik gelişimi,Türkiye Jeoloji Kurumu Yayınları, 7.57-85 .
14. Goodman. R.E..1980. Introduction to Rock Mechanics. John Wiley and Sons. New York. 478p.
15. Gökçeoğlu, C., Sönmez. H., Ercanoğlu, M., 2000. Discontinuity controlled probabilistic slope failure risk maps of the Altındağ (settlement) region in Turkey. Engineering Geology. 55, 277-296.
16. Hoek, E. ve Bray, J.198 I. Rock Slope Engineering. Institute of Mining and Metallurgy, London, 358 p.
17. Hoerger, S.F., ve Young. D.S., 1987. Predicting local rock mass behavior using geostatistics. In Proceedings of 28th Symposium in Rock Mechanics. Rotherdam. Balkema, 99-106.
18. ISRM. 1981. Rock Characterization, Testing and Monitoring-ISRM Suggested Methods, Pergamon Press, Oxford, Brown, E.T. (ed.), 211 p.
19. Kasapoglu, K.E., 1980. Ankara kentinin jeo-mühendislik özellikleri. Hacettepe Üniversitesi Yerbilimleri Enstitüsü, Ankara, Doçentlik Tezi, 206 s. (yayımlanmamış).
20. Kulalilake, P.H.S.W, 1988. State-of-the-art in stochastic joint geometry modeling. International Proceedings of 29th US Symposium on Rock Mechanics, University of Minnesota Minneapolis.
21. La Pointe, P.R., 1980. Analysis of the spatial variation in rock mass properties through geostalistics. International Proceedings of 21st Symposium on Rock Mechanics, Rolla, MO. 570-580.
22. Leung. C.F., Kheok, S.C., 1987. Computer aided analysis of rock slope stability. Rock Mechanics and Rock Engineering. 20, 111-122. Leung, C.F., Quek. S.T., 1995. Probabilistic stability analysis of excavations in jointed rock. Canadian Geotechnical Journal. 32: 397-407.
23. Leventhal. A.R., Barker. C.S., Ambrosis, L.P., 1992. Malanjkhve copper project-overview of the geotechnical investigation for optimum mining exploration. Regional Symposium on Rock Slopes, India, 69-78.
24. Marek, J.M., Savely, J.P., 1978. Probabilistic analysis of plane shear failure mode. International Proceedings of 19 th US Symposium on Rock Mechanics, 40-44.
25. McMahon, B.K., 1971. A statistical method for the design of rock slopes. International Proceedings of 1st Australia-New Zealand Conference on Geomechanics, 314-321.
26. McMahon, B.K., 1975. Probability of failure and expect volume of failure in high rock slopes. International Proceedings of 2nd Australia-New Zealand Conference on Geomechanics, Brisbane, Australia, 308-314.
27. Miller, S.M., 1983. A statistical method to evaluate homogeneity of structural populations. Mathematical Geology, Vol. 15 No. 2, 317-328.
28. Morris, P., Stotter, H.J., 1983. Open-cut design using probabilistic methods. In Proceedings of 5th International Congress on Rock Mechanics, Vo1.1, C107-113.
29. Norrish, N.I., Wyllie, D.C., 1996. Rock slope stability analysis. Landslide Investigation and Mitigation (Editors Turner and Schuster) Special Report 247. Transportation Research Board National Research Council. National Academy Press, Washington, 673 p.
30. Öcal, A.. Özgenoğlu. A.. 1995. A computer program for kinematic analysis of rock slopes. Proceedings of the 4th International Symposium on Mine Planning and Equipment Selection. Canada. 1005-1010.
31. Pilant, W.L., 1989. A PC interactive stereonet plotling program. Computers and Geosciences, 15 (1). 43-48.
32. Piteau, D.R., Martin, D.C., 1977. Slope stability analysis and design based on probability techniques al Cassiar Mine Canadian Mining Metallurgy Journal. March, 1-12.
33. Priest, S.D., 1985. Hemispherical Projection Methods in Rock Mechanics. George Allen and Unwin. Boston. 124 p.
34. Priest, S.D., ve Brown, E.T., 1983. Probabilistic stability analysis of variable rock slopes.Transportation Institute Mining Metallurgy, London, Vol.92
35. Sönmez, H.. Gökceoglu, C., 1998. A computer program for the kinematical analysis of rock slopes and its application, Earthsciences (Bull, of Earlhsciences Application and Research Center of Hacettepe University), 20, 75-89 (in Turkish).
36. Tharp. T.M., 1985. Stability analysis for three-plane wedges. Computers and Geosciences, 1 1 (4). 417-428.
37. Tuncay, E., 1999. TKİ-Himmetoğlu linyit açık işletmesindeki şevlerin duraylılığının deterministik ve olasılığa dayalı yöntemlerle değerlendirilmesi. Hacettepe Üniversitesi Fen Bilimleri Enstitüsü, Ankara, Yüksek Mühendislik Tezi. 165 s. (yayımlanmamış).
38. Ulusay, R., 1975. Ankara kenti kuzey-orta bölgesinin jeo-mühendislik özellikleri, Hacettepe Üniversitesi Yerbilimleri Enstitüsü, Ankara, Yüksek Mühendislik Tezi, 81 s. (yayımlanmamış).
39. Wu. T.H., Tang, W.H., Einstein, H.H., 1996. Lveslide Hazard and risk assessment. Landslides Investigation and Mitigation, (Editors Turner and Schuster) Special Report 247. Transportation Reseach Board National Research Council, National Academy Press, Washington, 673 p.
40. Young. D.S., 1993. Probabilistic slope analysis for structural failure. International Journal of Rock Mechanics Mining Science and Geomechanics Abstracts, Vol.30, No.7, 1623-1629.
41. Young, D.S., ve Hoerger, S.F., 1988. Geoslatsitics applications to rock mechanics. International Proceedings of 29 th US Symposium on Rock Mechanics, Minneapolis, MN, Brookfield, A.A. Balkema, 271-282.
42. Zanbak, C., 1977. Statistical interpretation of discontinuity contour diagram, International Journal of Rock Mechanics Mining Science and Geomechanics Abstracts, V.14, 114,120.
43. Zhang, S., ve Tong, G., 1988. Computerized pole concentration graphs using the Wulff stereographic projection. International Journal of Rock Mechanics and Mining Science and Geomechanics Abstracts, 23 (1), 45-51.