Geomechanics and Engineering

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Analysis for mechanical characteristics and failure models of coal specimens with non-penetrating single crack

  • Lv, Huayong (School of Resource and Safety Engineering, China University of Mining and Technology (Beijing)) ;
  • Tang, Yuesong (School of Resource and Safety Engineering, China University of Mining and Technology (Beijing)) ;
  • Zhang, Lingfei (School of Resource and Safety Engineering, China University of Mining and Technology (Beijing)) ;
  • Cheng, Zhanbo (School of Resource and Safety Engineering, China University of Mining and Technology (Beijing)) ;
  • Zhang, Yaning (School of Resource and Safety Engineering, China University of Mining and Technology (Beijing))
  • Received : 2019.01.07
  • Accepted : 2019.02.24
  • Published : 2019.03.20
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Abstract

It is normal to observe the presence of numerous cracks in coal body. And it has significantly effective on the mechanical characteristics and realistic failure models of coal mass. Therefore, this paper is to investigate the influence of crack parameters on coal body by comprehensive using theoretical analysis, laboratory experiments and numerical simulation through prepared briquette specimens. Different from intact coal body possessing single peak in stress-strain curve, other specimens with crack angle can be illustrated to own double peaks. Moreover, the unconfined compressive strength (UCS) of specimens decreases and follow by increasing with the increase of crack angle. It seems to like a parabolic shape with an upward opening. And it can be demonstrated that the minimum UCS is obtained in crack angle $45^{\circ}$. In terms of failure types, it is interesting to note that there is a changing trend from tensile failure to tensile-shear mixing failure with tension dominant follow by shear dominant with the increase of crack angle. However, the changing characteristics of UCS and failure forms can be explained by elastic-plastic and fracture mechanics. Lastly, the results of numerical simulations are good consistent with the experimental results. It provides experimental and theoretical foundations to reveal fracture mechanism of coal body with non-penetrating single crack further.

Keywords

Acknowledgement

Supported by : China University of Mining and Technology, China Scholarship Council (CSC)

References

  1. Bagheripour, M., Rahgozar, R. and Pashnesaz, H. (2011), "A complement to Hoek-Brown failure criterion for strength prediction in anisotropic rock", Geomech. Eng., 3(1), 61-81. https://doi.org/10.12989/gae.2011.3.1.061
  2. Cao, R., Cao, P. and Lin, H. (2017), "Experimental and numerical study of the failure process and energy mechanisms of rock-like materials containing cross un-persistent joints under uniaxial compression", Plos One, 12(12), e0188646. https://doi.org/10.1371/journal.pone.0188646
  3. Cen, D.F. and Huang, D. (2014), "Mesoscopic displacement modes of crack propagation of rock mass under uniaxial compression with high strain rate", J. China Coal Soc., 39(3), 436-444.
  4. Erarslan, N. (2016), "Microstructural investigation of subcritical crack propagation and fracture process zone (FPZ) by the reduction of rock fracture toughness under cyclic loading", Eng. Geol., 208, 181-190. https://doi.org/10.1016/j.enggeo.2016.04.035
  5. Erdogan, F. and Sih, G.C.J. (1963), "On crack extension in plates under plane loading and transverse shear", J. Basic Eng., 85(4), 519-527. https://doi.org/10.1115/1.3656897
  6. Fu, J., Zhang, X. and Zhu, W. (2017), "Simulating progressive failure in brittle jointed rock masses using a modified elasticbrittle model and the application", Eng. Fract. Mech., 178, 212-230. https://doi.org/10.1016/j.engfracmech.2017.04.037
  7. Goncalves da Silva, B. and Einstein, H.H. (2013), "Modelling of crack initiation, propagation and coalescence in rocks", Int. J. Fracture, 182(2), 167-186. https://doi.org/10.1007/s10704-013-9866-8
  8. Gou, S.H. and Sun, Z.Q. (2002), "Closing law and stress intensity factor of elliptical crack under compressive loading", Trans. Nonferr. Metal. Soc., 5(12), 966-969.
  9. Haeri, H., Khaloo, A. and Marji, M.F. (2015), "Experimental and numerical simulation of the microcrack coalescence mechanism in rock-like materials", Strength Mater., 47(5), 740-754. https://doi.org/10.1007/s11223-015-9711-6
  10. Haeri, H., Shahriar, K. and Marji, M.F. (2014), "Experimental and numerical study of crack propagation and coalescence in precracked rock-like disks", Int. J. Rock. Mech. Min. Sci., 67, 20-28. https://doi.org/10.1016/j.ijrmms.2014.01.008
  11. Hatheway, H.W. (2009), "The complete ISRM suggested methods for rock characterization, testing and monitoring, 1974-2006", Environ. Eng. Geosci., 15(1), 47-48. https://doi.org/10.2113/gseegeosci.15.1.47
  12. Jaeger, J.C. and Cook, N.G. (1981), Rock Mechanics Foundation, Science Press, Beijing, China.
  13. Komurlu, E., Kesimal, A. and Demir, S. (2016), "Experimental and numerical analyses on determination of indirect (splitting) tensile strength of cemented paste backfill materials under different loading apparatus", Geomech. Eng., 10(6), 775-791. https://doi.org/10.12989/gae.2016.10.6.775
  14. Li L.Y., Xu, F.G., Gao, F., Wang, L. and Che, F.X. (2005), "Fracture mechanics analysis of rock bridge failure mechanism", Chin. J. Rock Mech. Eng., 24(23), 4328-4334.
  15. Liu, C.Y., Huang, B.X., Chang, X.M., Wang, J. and Wei, M.T. (2008), "Study on tip to face coal and rock stability control of fully mechanized stepped large cutting height mining in extremely soft thick seam", J. China U. Min. Technol., 37(6), 734-739. https://doi.org/10.3321/j.issn:1000-1964.2008.06.002
  16. Liu, J.J. and Chen, L.Y. (2014), "Numerical analysis on strength characteristics of sandstone samples failure with single fracture in the condition of uniaxial compression", Sci. Technol. Eng., 14(25), 282-287, 292.
  17. Lu, Y., Wang, L. and Elsworth, D. (2015), "Uniaxial strength and failure in sandstone containing a pre-existing 3-D surface flaw", Int. J. Fracture, 194(1), 59-79. https://doi.org/10.1007/s10704-015-0032-3
  18. Mohammadi, M. and Tavakoli, H. (2015), "Comparing the generalized Hoek-Brown and Mohr-Coulomb failure criteria for stress analysis on the rocks failure plane", Geomech. Eng., 9(1), 115-124. https://doi.org/10.12989/gae.2015.9.1.115
  19. Panaghi, K., Golshani, A. and Takemura, T. (2015), "Rock failure assessment based on crack density and anisotropy index variations during triaxial loading tests", Geomech. Eng., 9(6), 793-813. https://doi.org/10.12989/gae.2015.9.6.793
  20. Sagong, M. and Bobet, A. (2002), "Coalescence of multiple flaws in a rock-model material in uniaxial compression", Int. J. Rock. Mech. Min. Sci., 39(2), 229-241. https://doi.org/10.1016/S1365-1609(02)00027-8
  21. Sarfarazi, V., Haeri, H., Marji, M.F. and Zhu, Z.M. (2017), "Fracture mechanism of brazilian discs with multiple parallel notches using PFC2D", Period. Polytech. Civ. Eng., 61(4), 653-663.
  22. Shen, B. and Barton, N (2018), "Rock fracturing mechanisms around underground openings", Geomech. Eng., 16(1), 35-47. https://doi.org/10.12989/gae.2018.16.1.035
  23. Song, X.M. (1998), "Correlation between distribution of cracks and fissures in top coal and size of fragment of mining with sublevel caving", J. China Coal Soc., 23(2), 40-44.
  24. Sun, W., Zhang, S., Guo, W. and Liu W. (2017), "Physical simulation of high-pressure water inrush through the floor of a deep mine", Min. Water Environ., 36(4), 542-549. https://doi.org/10.1007/s10230-017-0443-7
  25. Sun, X.Z., Shen, B. and Zhang, B.L. (2018), "Experimental study on propagation behavior of three-dimensional cracks influenced by intermediate principal stress", Geomech. Eng., 14(2), 195-202. https://doi.org/10.12989/GAE.2018.14.2.195
  26. Tang, C.A. (1998), "Numerical simulation of loading inhomogeneous rocks", Int. J. Rock. Mech. Min. Sci., 35(7), 1001-1007. https://doi.org/10.1016/S0148-9062(98)00014-X
  27. Tang, C.A. (2000), "Numerical studies of the influence of microstructure on rock failure in uniaxial compression-Part I: Effect of heterogeneity", Int. J. Rock. Mech. Min. Sci., 37(4), 555-569. https://doi.org/10.1016/S1365-1609(99)00121-5
  28. Tang, C.A. (2000), "Numerical studies of the influence of microstructure on rock failure in uniaxial compression-Part II: Constraint, slenderness and size effect", Int. J. Rock. Mech. Min. Sci., 37(4), 571-583. https://doi.org/10.1016/S1365-1609(99)00122-7
  29. Wang, J.C. (2018), "Engineering practice and theoretical progress of top-coal caving mining technology in China", J. China Coal Soc., 43(1), 43-51.
  30. Wang, J.C. and Yang, S.L. (2009), "Numerical simulation of mining effect on collapse column activated water Conducting mechanism", J. Min. Saf. Eng., 26(2), 140-144. https://doi.org/10.3969/j.issn.1673-3363.2009.02.002
  31. Wang, S.Y., Sloan, S.W. and Sheng, D.C. (2014), "Numerical study of failure behaviour of pre-cracked rock specimens under conventional triaxial compression", Int. J. Solids Struct., 51(5), 1132-1148. https://doi.org/10.1016/j.ijsolstr.2013.12.012
  32. Wang, X. and Tian, L. (2018), "Mechanical and crack evolution characteristics of coal-rock under different fracture-hole conditions: A numerical study based on particle flow code", Environ. Earth Sci., 77(8), 297. https://doi.org/10.1007/s12665-018-7486-3
  33. Wang, Z.H. (2017), "Failure mechanism and cavability evaluation of the top coal in longwall top-coal caving mining", Ph.D. Dissertation, China University of Mining and Technology (Beijing), Beijing, China.
  34. Yang, L., Jiang, Y. and Li, S. (2013), "Experimental and numerical research on 3D crack growth in rocklike material subjected to uniaxial tension", J. Geotech. Geoenviron. Eng., 139(10), 1781-1788. https://doi.org/10.1061/(ASCE)GT.1943-5606.0000917
  35. Yang, S.L., Jiang, H. and Cheng, Z.H. (2013), "Mechanism and control Technology of rib spalling in hard coal seam with developed beddings", Coal Sci. Technol., 41(12), 27-30.
  36. Zhang, Y. and Wu, J. (2000), "Crack-movement degree and caving characteristic of top-coal in longwall top-coal caving mining", J. China U. Min. Technol., 29(5), 506-509. https://doi.org/10.3321/j.issn:1000-1964.2000.05.016
  37. Zhao, X.G., Cai, M. and Wang, J. (2015), "Objective determination of crack initiation stress of brittle rocks under compression using AE measurement", Rock Mech. Rock. Eng., 48(6), 2473-2484. https://doi.org/10.1007/s00603-014-0703-9
  38. Zhou, X., Zhang, J. and Wong, L. (2018), "Experimental study on the growth, coalescence and wrapping behaviors of 3D Cross-Embedded flaws under uniaxial compression", Rock Mech. Rock. Eng., 51(5), 1379-1400. https://doi.org/10.1007/s00603-018-1406-4
  39. Zhou, X.P., Bi, J. and Qian, Q.H. (2015), "Numerical simulation of crack growth and coalescence in rock-like materials containing multiple pre-existing flaws", Rock Mech. Rock. Eng., 48(3), 1097-1114 https://doi.org/10.1007/s00603-014-0627-4

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