Hakan KARSLI, Ali Erden BABACAN, Mustafa ŞENKAYA, Kenan GELİŞLİ

P- ve S-dalga hızları ile jeolojik birimlerin sökülebilirliği üzerine bir değerlendirme

Sismik P- ve S- dalga hızları içinde yayıldıkları jeolojik birimlerin (zemin, kaya) fiziksel özelliklerine, ayrışma ve kırık-çatlak derecelerine, derinlik ve gözenek yapısına doğrudan bağlı olup, kazı çalışmalarında sökülebilirliğin tahmin edilmesinde yaygın olarak kullanılmaktadır. Jeolojik birimlerin P- ve S-dalga hızları arazide sırasıyla sismik kırılma ve çok kanallı yüzey dalgası analizi (ÇKYDA) yöntemleri ile belirlenebilir. Sismik hızların 1 ve 2 boyutlu (1B ve 2B) dağılımları ile jeolojik birimlerin jeoteknik nitelikleri ile ilişkili olarak sökülebilirlik sınıfları hızlı ve güvenilir olarak tahmin edilebilir. Bu çalışmada, Trabzon il merkezinde dört farklı alanda yapılan sismik ölçümlerden elde edilen veriler, ölçüm alanlarındaki jeolojik birimlerin sökülebilirlikleri için uluslararası standartlara (Caterpillar ve NEHRP) göre hazırlanmış P- ve S-dalga hızı sınıflama tabloları kullanılarak yeniden değerlendirilmiş ve S-dalga hızının dahil edildiği ilksel bir sismik hız-sökülebilirlik-jeoteknik sınıflama tablosu oluşturulmuştur. Böylece, jeolojik birimlerin türü (zemin, kaya) ve mekanik özelliği (sıkı, katı, sert) S-dalga hızına, sökülebilirlik dereceleri ise, P-dalga hızına göre tanımlanmıştır. Buna göre, genel olarak, çalışma alanlarındaki jeolojik birimler çok kolay-kolay sökülebilir az sıkı zemin (Vp<900 m/s, Vs<300 m/s), orta derecede sökülebilir katı- sıkı zemin (Vp900-1500 m/s, Vs400-600 m/s), zor sökülebilir çok sıkı-katı veya ayrışmış kaya (Vp1500-2100 m/s, Vs600-800 m/s), çok zor-son derece zor sökülebilir sağlam kaya (Vp2100-2400 m/s, Vs800-1100 m/s) ve sökülemez sert kaya (Vp>2400 m/s, Vs>1100 m/s) şeklinde sınıflandırılmıştır. Ayrıca, 2B P-dalga hızı-derinlik kesitleri sayesinde jeolojik birimlerin yaklaşık sınırlarının belirlenebileceği gösterilmiştir. Sonuç olarak, P- ve S-dalga hızlarının birlikte değerlendirilmesinin jeolojik birimin sökülebilirliğinin yanında, türü (zemin veya kaya), mekanik ve fiziksel özellikleri hakkında da bilgi vermektedir ve böylece sökülebilirlik tahmin hatalarının azaltılmasına ve kazı çalışmalarının yönlendirilmesine önemli katkılar sağlayacaktır.

Anahtar Kelimeler:

Sismik P- ve S-dalga hızları, Sökülebilirlik, Trabzon İli

An evaluation on rippability of geological units by seismic P- and S-wave velocities

Seismic P- and S- wave velocities are directly dependent on the physical properties of the geological units (soil and rock) in which they propagate, the degree of decomposition and fracture-crack, depth and porosity, and are widely used in estimating the rippability in excavation works. P- and S-wave velocities of geological units can be determined by seismic refraction and multichannel surface wave analysis (MASW) methods, respectively, in the field. The rippability classes can be estimated quickly and reliably in relation to the distribution of the seismic velocities in 1 and 2 dimensions (1D and 2D) and geotechnical characteristics of geological units. In this study, data from many in situ seismic measurements performed in four different areas in vicinity of center of Trabzon province were re-evaluated using P- and S-wave velocity classification tables prepared according to international standards (Caterpillar and NEHRP) for the rippability of geological units in the measurement areas and a primary seismic velocity-rippability-geotechnical classification table was prepared by including S-wave velocity. Therefore, the type (soil, rock) and mechanical property (firm, solid, hard, etc.) of the geological units are defined according to the S-wave velocity and the degree of rippability according to the P-wave velocity. Accordingly, in general, the geological units in the study areas are classified as very easy-to-easy, less firm soil (Vp <900 m/s, Vs <300 m/s), moderately rippabile solid- firm soil (Vp900-1500 m/s, Vs400-600 m/s), hard to rippabile very firm-solid or weathered rock (Vp1500-2100 m/s, Vs600-800 m/s), very hard-to-extremely hard to rippabile solid rock (Vp2100-2400 m/s, Vs800-1100 m/s) and non-rippabile hard rock (Vp>2400 m/s, Vs>1100 m/s). In addition, it has been shown that the approximate limits of geological units on 2D P-wave velocity-depth sections. Consequently, the evaluation of P- and S-wave velocities together has provided the information about the type (soil or rock), mechanical and physical properties of the geological units besides the rippability, thus will ensure minimizing the rippability estimation errors and to the guiding of excavation works.

Keywords:

Seismic P- and S-wave velocities, Rippability, Trabzon Province,

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[1] Braybrooke JC. “The state of the art of rock cuttability and rippability prediction”. Proceeding 5th Australian-New Zealand Conference Geomechanics, Sydney, 22-26 August 1998.
[2] Pettifer G, Fookes P. “A revision of the graphical method for assessing the excavatability of rock”. Quarterly Journal of Engineering Geology and Hydrogeology, 27(2), 145-164, 1994.
[3] McCann DM, Fenning PJ. “Estimation of rippability and excavation conditions from seismic velocity measurements”. Engineering Geology of Construction, Geological Society Engineering Geology Special Publication 10, 335-343, 1995.
[4] Karpuz C. “A classification system for excavation of surface coal measures”. Mining Science Technology, 11(2), 157-163, 1990.
[5] Başarır H, Karpuz C. “A rippability classification system for marls in lignite mines”. Engineering Geology, 74(3-4), 303-318, 2004.
[6] Komatsu. Specifications and Application Handbook. 10nd ed. Komatsu, Akasaka, Minato-ku, Tokyo, Japan, 1987.
[7] Caterpillar Tractor Company. Caterpillar Performance Handbook. 19nd ed. Caterpillar, Peoria, IL, USA, 1988.
[8] Bailey AD. “Rock types and seismic velocities versus rippability”. Proceedings of the 26th Annual Highway Geology Symposium, Coeur d’Alene, Idaho, 13–15 August 1975.
[9] Tonnizam ME, Rosli S, Muhazian M, Fauzi M. “Assessment on excavatability in weathered sedimentary rock mass using seismic velocity method”. Journal of Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing, 1(2), 258-263, 2011.
[10] Dindarloo SR, Siami-Irdemoosa E. “Ground Rippability Classification By Decision Trees”. Transactions of the Society for Mining, Metallurgy, and Exploration, 338(1), 112-121, 2015.
[11] Ismail MA, Kumar NS, Abidin MHZ, Madun A. “Rippability assessment of weathered sedimentary rock mass using seismic refraction methods”. Journal of Physics Conference Series, 2018. https://doi.org/10.1088/1742-6596/995/1/012105.
[12] Atkinson T. “Selection of open pit excavating and loading equipment”. Transactions of the Institution of Mining Metalurgy, 80, A101-A129, 1971.
[13] Church HK. Excavation Handbook, 1st ed. New York, USA, McGraw-Hill, 1981.
[14] Göktan RM, İphar M. “Açık işletmelerde kayaç sökülebilirlik tayin yöntemleri”. MT Bilimsel Yeraltı Kaynakları Dergisi, 2(3), 1-16, 2013.
[15] Choudhury PB, Chakraborty AK, Sitharam TG. “Near Surface Vs Profiling Using MASW for Rippability Assessment of Milliolithic Limestone”. International Society for Rock Mechanics and Rock Engineering, University of Hong Kong, China, 19-22 May 2009.
[16] Campbell N, Fenton C, Williams ST. An Investigation into the Effects of Material Properties on Shear Wave Velocity in Rocks/Soils, Editors: Lehane BM, Acosta-Martinez HE, Kelly R. Geotechnical and Geophysical Site Characterisation, 849-855, Sydney, Australia, Australian Geomechanics Society, 2016.
[17] Moustafa SS, Ibrahim EH, Elawadi E, Metwaly M, Al Agami N. “Seismic refraction and resistivity imaging for assessment of groundwater seepage under a Dam site, Southwest of Saudi Arabia". International Journal of Physical Sciences, 7(48), 6230-6239, 2013.
[18] Caterpillar Tractor Company. Caterpillar performance handbook. 40th ed. Peoria, Illinois, USA, Caterpillar, 2010.
[19] National Earthquake Reduction Program (NEHRP). "Recommended provisions for seismic regulations for new buildings and other steel structures, Part 1: Provisions". Washington, USA, 2003.
[20] Bailey AD. "Refraction seismic on advancing tool". The Mines Magazine, 64(1), 1-11, 1974.
[21] Öncel K. Kayaç ve Zeminlerin Yapı ve Doku Özellikleriyle Sökülebilirlikleri ve P Tipi Dalga Hizlari Arasindaki Ilişki. 1. Baskı. Ankara, Türkiye, İller Bankası Genel Müdürlüğü, Su ve Kanalizasyon Dairesi Başkanlığı, 1979.
[22] Weaver J. Geological factors significant in the assessment of rippability. The Civil Engineering in South Africa, 17(12), 313-316, 1975.
[23] Bieniawski ZT. Engineering rock mass classifications: a complete manual for engineers and geologists in mining, civil, and petroleum engineering. 1st ed. Newyork, USA, John Wiley and Sons, 1989.
[24] McCormick Jr WN. "Engineering and Design: Rock Mass Classification Data Requirements for Rippability". Department of Army USA Army Corps of Engineers, Washington, USA, Technical Letter 110-2-282, 1983.
[25] El-Naqa A. "Assessment of geomechanical characterization of a rock mass using a seismic geophysical technique". Geotechnical and Geological Engineering, 14, 291-305, 1996.
[26] Uyanık O, Sabbağ N, Uyanık N.A, Öncü Z. "Prediction of mechanical and physical properties of some sedimentary rocks from ultrasonic velocities". Bulletin of Engineering Geology and the Environment, 78(8), 6003-6016, 2019.
[27] Watkins JS, Walters LA, Godson RH. "Dependence of in-situ P-wave velocity on porosity". Geophysics, 37(1), 29-35, 1972.
[28] Toksoz MN, Cheng CH, Timur A. "Velocities of seismic waves in porous rocks". Geophysics, 41(4), 621-645, 1976.
[29] Salem HS. "Poisson's ratio and the porosity of surface soils and shallow sediments determined from seismic P- and s-wave velocities". Geotechnique, 50(4), 461-463, 2000.
[30] Uyanık O. "The porosity of saturated shallow sediments from seismic compressional and shear wave velocities". Journal of Applied Geophysics, 73(1), 16-24, 2011.
[31] Keçeli A. “Sismik Hızlar ile Saptanabilen Zemin Parametreleri”. Jeofizik, 26(1), 17-29, 2012.
[32] Church HK. "Geophysical Examination Can Make Earth-Moving a Profitable Science in the Southwest". Southwest Builder and Contractor, USA, 13, 1964.
[33] Mohamad ET, Kassim KA, Komoo I. “An overview of existing rock excavatability assessment techniques”. Jurnal Kejuruteraan Awam, 17(2), 46-59, 2005.
[34] Geometrics. "SeisImager/2D Software Manual". https://www.geometrics.com/software/ (10.03.2020).