SPECIMEN GEOMETRY AND LOADING RATE CONDITION EFFECT ON INDIRECT TENSILE STRENGTH VALUES OF ROCK MATERIALS

Öz

In this study, rock core specimens with same diameter and different length to diameter ratios were tested under deformation controlled and load controlled various loading rate conditions. According to the results obtained from 5 different types of rock material and 90 specimens tested in this study, measured indirect tensile strength values were found to significantly increase with a decrease in the ratio of length to diameter under load controlled loading rate (kN/s) condition. To minimize the effect of geometry of the specimens and obtain similar results from specimens with different length to diameter ratios, the indirect tensile strength (Brazilian) test was suggested to carry out under the condition of deformation controlled loading rate (mm/min) selection.

Anahtar Kelimeler

• Indirect Tensile Strength,Brazilian Test,Rock Mechanics Experiments,Specimen Geometry,Loading Rate

NUMUNE GEOMETRİSİ VE YÜKLEME HIZI KOŞULLARININ KAYA MALZEMELERİ DOLAYLI ÇEKME DAYANIMI DEĞERLERİ ÜZERİNDEKİ ETKİLERİ

Öz

Bu çalışmada, aynı çap ve farklı boy/çap oranlarına sahip kaya malzemesi numuneleri deformasyon kontrollü ve yük kontrollü olarak farklı yükleme hızı koşullarında test edilmiştir. 5 farklı kaya malzemesi ve toplam 90 adet dolaylı çekme dayanımı (Brezilyan) testi numunelerinden elde edilen sonuçlara göre, yük kontrollü bir yükleme hızı (kN/s) seçimi koşulunda boy/çap oranı artışı ile hesaplanan dayanım değerlerinde belirgin ölçüde azalma olduğu görülmüştür. Numune geometrisi etkisinin minimize edilmesi, farklı boy/çap oranlarına sahip numunelerden benzer dayanım değerlerinin elde edilmesi için deformasyon kontrollü yükleme hızı (mm/dakika) seçilerek dolaylı çekme dayanımı testlerinin gerçekleştirilmesi önerilmiştir.

Anahtar Kelimeler

• Dolaylı Çekme Dayanımı,Brezilyan Testi,Kaya Mekaniği Deneyleri,Numune Geometrisi,Yükleme Hızı

Kaynakça

1. Akazawa, T., 1943. New test method for evaluating internal stress due to compression of concrete (the splitting tension test) (part 1). Journal of Japan Society of Civil Engineering, 29, 777-787.
2. Aliha, M.R.M., 2014. Indirect tensile test assessments for rock materials using 3-D disc-type specimens. Arabian Journal of Geosciences, 7 (11), 4757–4766.
3. ASTM D3967-16, 2016. Standard Test Method for Splitting Tensile Strength of Intact Rock Core Specimens. ASTM International, West Conshohocken, PA.
4. Carneiro, F.L.L.B., 1943. A new method to determine the tensile strength of concrete. Proceedings of the 5th meeting of the Brazilian Association for Technical Rules, September 1943, 126-129.
5. Erarslan, N., Liang, Z.Z., Williams, D.J., 2012. Experimental and Numerical Studies on Determination of Indirect Tensile Strength of Rocks. Rock Mechanics and Rock Engineering, 45(5), 739-751.
6. Fabjan, T., Ivars D.M., Vukadin, V., 2015. Numerical simulation of intact rock behaviour via the continuum and Voronoi tesselletion models – a sensitivity analysis. Acta Geotechnica Slovenica, 12, 5-23.
7. Fairbairn, E.M.R., Ulm, J.F., 2002. A Tribute to Fernando L. L. B. Carneiro (1913 - 2001) Engineer and Scientist who invented the Brazilian Test. Materials and Structures, 35, 195-196.
8. Gong, F.Q., Zhao, G.F., 2014. Dynamic Indirect Tensile Strength of Sandstone under Different Loading Rates. Rock Mechanics and Rock Engineering, 47, 2271-2278.

9. Gong, F., Zhang, L., Wang, S., 2019. Loading Rate Effect of Rock Material with the Direct Tensile and Three Brazilian Disc Tests. Advances in Civil Engineering, vol. 2019, Article ID 6260351, 8 pages
10. Guinea, G.V., Elices, M., Planas, J., 2000. Assessment of the tensile strength through size effect curves. Engineering Fracture Mechanics, 65, 189-207.
11. Huafeng, D., Jianlin, L., Min, Z., Ruihong, W., Xianfan, Y., Qian, L., 2012. Research on effect of disc thickness-to-diameter ratio on splitting tensile strength of rock. Chinese Journal of Rock Mechanics and Engineering, 31, 792-798
12. ISRM, 1978. International society for rock mechanics suggested methods for determining tensile strength of rock materials. International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts, 15, 99–103.
13. ISRM, 2007. The blue book - the complete ISRM suggested methods for rock characterisation, testing and monitoring: 1974-2006 (Ulusay R, Hudson JA in eds). ISRM & Turkish National Group of ISRM, Ankara
14. Jianhong, Y., Wu, F.Q., Sun, J.Z., 2009. Estimation of the tensile elastic modulus using Brazilian disc by applying diametrically opposed concentrated loads. International Journal of Rock Mechanics and Mining Sciences, 46, 568–576.
15. Kohmura, Y., Inada, Y., 2006. The Effect of the Loading Rate on Stress-Strain Characteristics of Tuff. Journal of the Society of Materials Science Japan, 55, 323-328.
16. Komurlu, E., 2018. Loading Rate Conditions and Specimen Size Effect on Strength and Deformability of Rock Materials under Uniaxial Compression. International Journal of Geo-Engineering, 9, Paper no: 17, 1-11.
17. Komurlu, E., 2019. An Experimental Study on Determination of Crack Propagation Energy of Rock Materials under Dynamic (Impact) and Static Loading Conditions. Hittite Journal of Science and Engineering, 6, 1-6.
18. Komurlu, E., Kesimal, A., 2012. Jaw Effects on Indirect Tensile Strength Test Disc Failure Mechanism. 7th Asian Rock Mechanics Symposium, October, Seoul, 624-637.
19. Komurlu, E., Kesimal, A., 2015. Evaluation of Indirect Tensile Strength of Rocks using Different Types of Jaws. Rock Mechanics and Rock Engineering, 48, 1723-1730.
20. Komurlu, E., Kesimal, A., Demir, S., 2016. An Experimental and Numerical Study on Determination of Indirect (Splitting) Tensile Strength of Rocks under Various Load Apparatus. Canadian Geotechnical Journal, 53, 360-372.
21. Kömürlü, E., Kesimal, A., 2017. Darbe Etkisi Altında Granit Türü Farklı Kaya Malzemelerinin Çatlak İlerleme Enerjisinin Belirlenmesi Üzerine Deneysel Bir Çalışma. Ulusal Mühendislik Jeolojisi ve Geoteknik Sempozyumu 2017, Ekim, Adana, 231-238.
22. Kourkoulis, S.K., Markides, C.F., Chatzistergos, P.E., 2013. The standardized Brazilian disc test as a contact problem. International Journal of Rock Mechanics and Mining Science, 57, 132-141.
23. Li, X., Marasteanu, M.O., Williams R.C., 2007. The Effect of Loading Level and Rate in the Indirect Tensile Test. Proceedings of the 2007 Mid-Continent Transportation Research Symposium, Ames, Iowa,
24. Lin, H, Xiong, W., Yan, Q., 2016. Three-Dimensional Effect of Tensile Strength in the Standard Brazilian Test Considering Contact Length. Geotechnical Testing Journal, 39 (1), 137-143.
25. Markides, C.F., Kourkoulis, S.K., 2013. Naturally Accepted Boundary Conditions for the Brazilian Disc Test and the Corresponding Stress Field. Rock Mechanics and Rock Engineering, 46, 959-980.
26. Markides, C.F., Kourkoulis, S.K., 2016. The influence of jaw’s curvature on the results of the Brazilian disc test. Journal of Rock Mechanics and Geotechnical Engineering, 8, 127-146.
27. Markides, C.F., Pazis, D.N., Kourkoulis, S.K., 2010. Closed Full-Field Solutions for Stresses and Displacements in the Brazilian Disc under Distributed Radial Load. International Journal of Rock Mechanics and Mining Science, 47 (2), 227–237.
28. Xu, X., Wu, S., Gao, Y., Xu M., 2016. Effects of Micro-structure and Micro-parameters on Brazilian Tensile Strength Using Flat-Joint Model. Rock Mechanics and Rock Engineering, 49 (9), 3575–3595.
29. Ye, J.H., Wu, F.Q., Zhang, Y., Ji, H.G., 2012. Estimation of the bi-modulus of materials through deformation measurement in a Brazilian disk test. International Journal of Rock Mechanics and Mining Sciences, 52, 122–131.
30. Yu, M., Wei, C., Niu, L., 2017. The Coupled Effect of Loading Rate and Grain Size on Tensile Strength of Sandstones under Dynamic Disturbance. Shock and Vibration, Cilt. 2017, Article ID 6989043, 13 pages.
31. Yu, Y., Yin, J., Zhong, Z., 2006. Shape effects in the Brazilian tensile strength test and a 3D FEM correction. International Journal of Rock Mechanics and Mining Sciences, 43, 623-627