Geomechanics and Engineering

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Experimental and numerical investigation of the effect of sample shapes on point load index

  • Haeri, Hadi (Young Researchers and Elite Club, Bafgh Branch, Islamic Azad University) ;
  • Sarfarazi, Vahab (Department of Mining Engineering, Hamedan University of Technology) ;
  • Shemirani, Alireza Bagher (Department of Civil Engineering, Sadra Institute of Higher Education) ;
  • Hosseini, Seyed Shahin (Department of Civil Engineering, Aria University of Sciences and Sustainability)
  • Received : 2017.02.02
  • Accepted : 2017.05.20
  • Published : 2017.12.25
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Abstract

Tensile strength is considered key properties for characterizing rock material in engineering project. It is determined by direct and indirect methods. Point load test is a useful testing method to estimate the tensile strengths of rocks. In this paper, the effects of rock shape on the point load index of gypsum are investigated by PFC2D simulation. For PFC simulating, initially calibration of PFC was performed with respect to the Brazilian experimental data to ensure the conformity of the simulated numerical models response. In second step, nineteen models with different shape were prepared and tested under point load test. According to the obtained results, as the size of the models increases, the point load strength index increases. It is also found that the shape of particles has no major effect on its tensile strength. Our findings show that the dominant failure pattern for numerical models is breaking the model into two pieces. Also a criterion was rendered numerically for determination of tensile strength of gypsum. The proposed criteria were cross checked with the results of experimental point load test.

Keywords

References

  1. American Society for Testing and Materials (ASTM) (2008), Standard Test Method for Determination of the Point Load Strength Index of Rock and Application to Rock Strength Classifications, ASTM International, West Conshohocken, Pennsylvania, U.S.A.
  2. Ayatollahi, M.R. and Alborzi, M.J. (2013), "Rock fracture toughness testing using SCB specimen", Proceedings of the 13th International Conference on Fracture, Beijing, China, June.
  3. Bagi, K. (2012), Fundamentals of the Discrete Element Method, Lecture Notes, BME Faculty of Civil Engineering, Budapest, Hungary.
  4. Basu, A. and Aydin, A. (2006), "Predicting uniaxial compressive strength by point load test: Significance of cone penetration", Rock Mech. Rock Eng., 39(5), 483-490. https://doi.org/10.1007/s00603-006-0082-y
  5. Basu, A. and Kamran, M .(2010), "Point load test on schistose rocks and its applicability in predicting uniaxial compressive strength", J. Rock Mech. Min. Sci., 47(5), 823-828. https://doi.org/10.1016/j.ijrmms.2010.04.006
  6. Basu, A., Mishra, D.A. and Roychowdhury, K. (2013), "Rock failure modes under uniaxial compression, Brazilian, and point load tests", Bull. Eng. Geol. Environ., 72(3-4), 457-475. https://doi.org/10.1007/s10064-013-0505-4
  7. Bieniawski, Z.T. (1975), "The point-load test in geotechnical practice", Eng. Geol., 9(1), 1-11. https://doi.org/10.1016/0013-7952(75)90024-1
  8. Broch, E. and Franklin, J.A. (1972), "The point-load strength test", J. Rock Mech. Min. Sci. Geomech. Abstr., 9(6), 669-676. https://doi.org/10.1016/0148-9062(72)90030-7
  9. Celik, S.B. (2008), "Estimation of uniaxial compressive strength from point load strength, Schmidt hardness and P-wave velocity", Bull. Eng. Geol. Environ., 67(4), 491-498. https://doi.org/10.1007/s10064-008-0158-x
  10. Chau, K.T. and Wong, R.H.C. (1996), "Uniaxial compressive strength and point load strength of rocks", J. Rock Mech. Min. Sci. Geomech. Abstr., 33(2), 183-188.
  11. Fener, M., Kahraman, S., Bilgil, A. and Gunaydin, O. (2005), "A comparative evaluation of indirect methods to estimate the compressive strength of rocks", Rock Mech. Rock Eng., 38(4), 329-343. https://doi.org/10.1007/s00603-005-0061-8
  12. Haeri, H. (2015g), "Propagation mechanism of neighboring vracks in rock-like cylindrical specimens under uniaxial compression", J. Min. Sci., 51(3), 487-496. https://doi.org/10.1134/S1062739115030096
  13. Haeri, H. (2015h), "Simulating the crack propagation mechanism of pre-cracked concrete specimens under shear loading conditions", Strength Mater., 47(4), 618-632. https://doi.org/10.1007/s11223-015-9698-z
  14. Haeri, H., Khaloo, A. and Marji, M.F. (2015c), "Experimental and numerical simulation of the microcracks coalescence mechanism in rock-like materials", Strength Mater., 47(1), 740-754. https://doi.org/10.1007/s11223-015-9711-6
  15. Haeri, H., Khaloo, A. and Marji, M.F. (2015d), "A coupled experimental and numerical simulation of rock slope joints behavior", Arab. J. Geosci., 8(9), 7297-7308. https://doi.org/10.1007/s12517-014-1741-z
  16. Haeri, H., Khaloo, A. and Marji, M.F. (2015e), "Fracture analyses of different pre-holed concrete specimens under compression", Acta Mech. Sinica, 31(6), 855-870. https://doi.org/10.1007/s10409-015-0436-3
  17. Haeri, H., Khaloo, A. and Marji, M.F. (2015f), "Experimental and numerical analysis of Brazilian discs with multiple parallel cracks", Arab. J. Geosci., 8(8), 5897-5908. https://doi.org/10.1007/s12517-014-1598-1
  18. Haeri, H., Marji, M.F. and Shahriar, K. (2015b), "Simulating the effect of disc erosion in TBM disc cutters by a semi-infinite DDM", Arab. J. Geosci., 8(6), 3915-3927. https://doi.org/10.1007/s12517-014-1489-5
  19. Haeri, H., Shahriar, K., Marji, M.F. and Moarefvand, P. (2014a), "On the cracks coalescence mechanism and cracks propagation paths in rock-like specimens containing pre-existing random cracks under compression", J. Central South U., 21(6), 2404-2414. https://doi.org/10.1007/s11771-014-2194-y
  20. Haeri, H., Shahriar, K., Marji, M.F. and Moarefvand, P. (2014b), "Investigating the fracturing process of rock-like Brazilian discs containing three parallel cracks under compressive line loading", Strength Mater., 46(3), 133-148.
  21. Haeri, H., Shahriar, K., Marji, M.F. and Moarefvand, P. (2015b), "The HDD analysis of micro cracks initiation, propagation and coalescence in brittle substances", Arab. J. Geosci., 8(5), 2841-2852. https://doi.org/10.1007/s12517-014-1290-5
  22. Heidari, M., Khanlari, G., Torabi Kaveh, M. and Kargarian, S. (2012), "Predicting the uniaxial compressive and tensile strengths of gypsum rock by point load testing", Rock Mech. Rock Eng., 45(2), 265-273. https://doi.org/10.1007/s00603-011-0196-8
  23. International Society for Rock Mechanics (ISRM) (1985), "Suggested method for determining point load strength: ISRM common testing methods", Rock Mech. Min. Sci. Geomech. Abstr., 22(4), 112.
  24. Kahraman, S. and Gunaydin, O. (2009), "The effect of rock classes on the relation between uniaxial compressive strength and point load index", Bull. Eng. Geol. Environ., 68(3), 345-353. https://doi.org/10.1007/s10064-009-0195-0
  25. Kahraman, S., Gunaydin, O. and Fener, M. (2005), "The effect of porosity on the relation between uniaxial compressive strength and point load index", J. Rock. Mech. Min. Sci., 42(4), 584-589. https://doi.org/10.1016/j.ijrmms.2005.02.004
  26. Kayabal, K. and Selcuk, L. (2010), "Nail penetration test for determining the uniaxial compressive strength of rock", J. Rock. Mech. Min. Sci., 47(2), 265-271. https://doi.org/10.1016/j.ijrmms.2009.09.010
  27. Lee, S., Lee, S.H. and Chang, Y.S. (2015), "Evaluation of RPV according to alternative fracture toughness requirements", Struct. Eng. Mech., 53(6), 1271-1286. https://doi.org/10.12989/sem.2015.53.6.1271
  28. Li, D. and Wong, L.N.Y. (2013), "Point load test on meta-sedimentary rocks and correlation to UCS and BTS", Rock Mech. Rock Eng., 46(4), 889-896. https://doi.org/10.1007/s00603-012-0299-x
  29. Ma, G.W. and Wu, W. (2010), "Water saturation effects on sedimentary rocks", Civil Eng. Res., 23, 129-131.
  30. Mosabepranah, M.A. and Eren, O. (2016), "Statistical flexural toughness modeling of ultra high performance concrete using response surface method", Comput. Concrete, 17(4), 33-39.
  31. Protodyakonov, M.M. and Voblikov, V.S. (1957), "Determining the strength of rock on samples of an irregular shape", Ugol, 32(4).
  32. Rajabi, M., Soltani, N. and Eshraghi, I. (2016), "Effects of temperature dependent material properties on mixed mode crack tip parameters of functionally graded materials", Struct. Eng. Mech., 58(2), 144-156.
  33. Ramadoss, P. and Nagamani, K. (2013), "Stress-strain behavior and toughness of high-performance steel fiber reinforced concrete in compression", Comput. Concrete, 11(2), 55-65.
  34. Singh, T.N., Kainthola, A. and Venkatesh, A. (2012), "Correlation between point load index and uniaxial compressive strength for different rock types", Rock Mech. Rock Eng., 45(2), 259-264. https://doi.org/10.1007/s00603-011-0192-z
  35. Singh, V.K. and Singh, D.P. (1993), "Correlation between point load index and compressive strength for quartzite rocks", Geotch. Geol Eng., 11(4), 269-272. https://doi.org/10.1007/BF00466369
  36. Sonmez, H. and Osman, B. (2008), "The limitations of point load index for predicting of strength of rock material and a new approach", Proceedings of the 61st Geological Congress of Turkey, 1, 261-262.
  37. Sonmez, H., Gokceoglu, C., Medley, E.W., Tuncay, E. and Nefeslioglu, H.A. (2006), "Estimating the uniaxial compressive strength of a volcanic bimrock", J. Rock Mech. Min. Sci., 43(4), 554-561. https://doi.org/10.1016/j.ijrmms.2005.09.014
  38. Sonmez, H., Tuncay, E. and Gokceoglu, C. (2004), "Models to predict the uniaxial compressive strength and the modulus of elasticity for Ankara agglomerate", J. Rock Mech. Min. Sci., 41(5), 717-729. https://doi.org/10.1016/j.ijrmms.2004.01.011
  39. Tsiambaos, G. and Sabatakakis, N. (2004), "Considerations on strength of intact sedimentary rocks", Eng. Geol., 72(3), 261-273. https://doi.org/10.1016/j.enggeo.2003.10.001
  40. Wei, M.D., Dai, F., Xu, N.W., Xu, Y. and Xia, K. (2015), "Three-dimensional numerical evaluation of the progressive fracture mechanism of cracked chevron notched semi-circular bend rock specimens", Eng. Fract. Mech., 134, 286-303. https://doi.org/10.1016/j.engfracmech.2014.11.012
  41. Xu, N.W., Dai, F., Wei, M.D., Xu, Y. and Zhao, T. (2015a), "Numerical observation of three dimensional wing-cracking of cracked chevron notched Brazilian disc rock specimen subjected to mixed mode loading", Rock Mech. Rock Eng., 49(1), 79-96.
  42. Yaylac, M. (2016), "The investigation crack problem through numerical analysis", Struct. Eng. Mech., 57(6), 1143-1156. https://doi.org/10.12989/sem.2016.57.6.1143
  43. Yu, K. and Lu, Z. (2015), "Influence of softening curves on the residual fracture toughness of post-fire normal-strength concrete", Comput. Concrete, 15(2), 102-111.
  44. Zhou, Y.X., Xia, K., Li, X.B., Li, H.B., Ma, G.W., Zhao, J., Zhou, Z.L. and Dai, F. (2012), "Suggested methods for determining the dynamic strength parameters and mode-I fracture toughness of rock materials", J. Rock. Mech. Min. Sci., 49, 105-112. https://doi.org/10.1016/j.ijrmms.2011.10.004