Geomechanics and Engineering

Techno-Press (테크노프레스)
권호 표지
DOI QR코드

DOI QR Code

Influence of time-dependency on elastic rock properties under constant load and its effect on tunnel stability

  • Aksoy, C.O. (Department of Mining Engineering, Dokuz Eylul University) ;
  • Aksoy, G.G. Uyar (Department of Mining Engineering, Hacettepe University) ;
  • Guney, A. (Department of Mining Engineering, Mugla Sitki Kocman University) ;
  • Ozacar, V. (Torbali Vocational School, Dokuz Eylul University) ;
  • Yaman, H.E. (Department of Mining Engineering, Dokuz Eylul University)
  • Received : 2019.01.22
  • Accepted : 2019.12.10
  • Published : 2020.01.10
⟨ Previous Next ⟩

Abstract

In structures excavated in rock mass, load progressively increases to a level and remains constant during the construction. Rocks display different elastic properties such as Ei and ʋ under different loading conditions and this requires to use the true values of elastic properties for the design of safe structures in rock. Also, rocks will undergo horizontal and vertical deformations depending on the amount of load applied. However, under constant loads, values of Ei and ʋ will vary in time and induce variations in the behavior of the rock mass. In some empirical equations in which deformation modulus of the rock mass is taken into consideration, elastic parameters of intact rock become functions in the equation. Hence, the use of time dependent elastic properties determined under constant loading will yield more reliable results than when only constant elastic properties are used. As well known, rock material will play an important role in the deformation mechanism since the discontinuities will be closed due to the load. In this study, Ei and ʋ values of intact rocks were investigated under different constant loads for certain rocks with high deformation capabilities. The results indicated significant time dependent variations in elastic properties under constant loading conditions. Ei value obtained from deformability test was found to be higher than the Ei value obtained from the constant loading test. This implies that when static values of elastic properties are used, the material is defined as more elastic than the rock material itself. In fact, Ei and ʋ values embedded in empirical equations are not static. Hence, this workattempts to emerge a new understanding in designing of safer structures in rock mass by numerical methods. The use of time-dependent values of Ei and ʋ under different constant loads will yield more accurate results in numerical modeling analysis.

Keywords

Acknowledgement

Supported by : TUBITAK

This research was supported by TUBITAK. Project number is 114M566. Authors would like to TUBITAK (THE SCIENTIFIC AND TECHNOLOGICAL RESEARCH COUNCIL OF TURKEY) to give financial support.

References

  1. Agharazi, A., Tannant, D.D. and Martin, C.D. (2012), "Characterizing rock mass deformation mechanisms during plate load tests at the Bakhtiary dam project", Int. J. Rock Mech. Min. Sci., 49, 1-11. https://doi.org/10.1016/j.ijrmms.2011.10.002.
  2. Aksoy, C.O., Genis, M., Aldas, G.G., Ozacar, V., Ozer, S.C. and Yilmaz, O. (2012), "A comparative study of the determination of rock mass deformation modulus by using different empirical approaches", Eng. Geol., 131-132, 19-28. https://doi.org/10.1016/j.enggeo.2012.01.009.
  3. Aksoy, C.O., Uyar, G.G., Posluk, E., Ogul, K., Topal, I. and Kucuk, K. (2016), "Non-deformable support system application at tunnel-34 of Ankara-Istanbul high speed railway projec", Struct. Eng. Mech., 58(5), 869-886. http://dx.doi.org/10.12989/sem.2016.58.5.869.
  4. Bai, M., Meng, F., Elsworth, D. and Roegiers, J.C. (1999), "Analysis of stress-dependent permeability in nonorthogonal flow and deformation fields", Rock Mech. Rock Eng., 32(3), 195-219. https://doi.org/10.1007/s006030050032.
  5. Barla, G. (1999), "Tunneling under squeezing rock conditions", Proceedings of the International Conference on Rock Engineering Techniques for Site Characterisation, Bangalore, India.
  6. Bieniawski, Z.T. (1970), "Time-dependent behavior of fractured rock", Rock Mech., 2(3), 123-137. https://doi.org/10.1007/BF01239744.
  7. Brown, E.T., Bray, J.W. and Santarellil, F.J. (1979), "Influence of stress-dependent elastic moduli on stress and strains around axisymmetric boreholes", Rock Mech. Rock Eng., 22, 189-203. https://doi.org/10.1007/BF01470986.
  8. Duncan Fama, M.E. and Brown, E.T. (1989), "Influence of stress dependent elastic moduli on plane strain solution for boreholes", Proceedings of the International Symposium on Rock at Great Depth, Pau, France, August-September.
  9. Dyke, C.G. and Dobereiner, L, (1991), "Evaluating the strength and deformability of sandstones", Eng. Geol., 24, 123-134. https://doi.org/10.1144/GSL.QJEG.1991.024.01.13.
  10. Fabre, G. and Pellet, F. (2006), "Creep and time-dependent damage in argillaceous rocks", Int. J. Rock Mech. Min. Sci., 43, 950-960. https://doi.org/10.1016/j.ijrmms.2006.02.004.
  11. Gokceoglu, C., Sonmez, H. and Kayabasi, A. (2003), "Predicting the deformation moduli of rock masses", Int. J. Rock Mech. Min. Sci., 40, 701-710. https://doi.org/10.1016/S1365-1609(03)00062-5.
  12. Hoek, E. and Diederichs, M.S. (2006), "Empirical estimation of rock mass modulus", Int. J. Rock Mech. Min. Sci., 43, 203-215. https://doi.org/10.1016/j.ijrmms.2005.06.005.
  13. Houlsby, G.T., Amorosi, A. and Rojas, E. (2005), "Elastic moduli of soils dependent on pressure: A hyperelastic formulation", Geotechnique, 55(5), 383-392. https://doi.org/10.1680/geot.2005.55.5.383
  14. Gu, J. (2015), "Some practical considerations in designing underground station structures for seismic loads", Struct. Eng. Mech., 54(3), 491-500. http://dx.doi.org/10.12989/sem.2015.54.3.491.
  15. Kayabasi, A. Gokceoglu, C. and Ercanoglu, M. (2003), "Estimating the deformation modulus of rock masses: a comparative study", Int. J. Rock Mech. Min. Sci., 40(1), 55-63. https://doi.org/10.1016/S1365-1609(02)00112-0.
  16. Matsuki, K., Wang, E.Q., Sakaguchi, K. and Okumura, K. (2001), "Time-dependent closure of a fracture with rough surfaces under constant normal stress", Int. J. Rock Mech. Min. Sci., 38, 607-619. https://doi.org/10.1016/S1365-1609(01)00022-3.
  17. Mitri, H.S., Edrissi, R. and Henning, J. (1994), "Finite element modelling of cable-bolted stopes in hardrock ground mines", Proceedings of the SME Annual Meeting, Albuquerque, New Mexico, U.S.A., February.
  18. Palchik, V. (2018), "Applicability of exponential stress-strain models for carbonate rocks", Geomech. Eng., 15(3), 919-925. https://doi.org/10.12989/gae.2018.15.3.919.
  19. Palmstrom, A. and Singh, R. (2001), "The deformation modulus of rock masses-comparisons between in situ tests and indirect estimates" Tunn. Undergr. Sp. Technol., 16(3), 115-131. https://doi.org/10.1016/S0886-7798(01)00038-4.
  20. Rooh, A., Nejati, H.R. and Goshtasbi, K. (2018), "A new formulation for calculation of longitudinal displacement profile (LDP) on the basis of rock mass quality", Geomech. Eng., 16(5), 539-545. https://doi.org/10.12989/gae.2018.16.5.539.
  21. Sone, H. and Zoback, M.D. (2014), "Time-dependent deformation of shale gas reservoir rocks and its long-term effect on the insitu state of stress", Int. J. Rock Mech. Min. Sci., 69, 120-132. https://doi.org/10.1016/j.ijrmms.2014.04.002.
  22. Taravati, H. and Ardakani, A. (2018), "The numerical study of seismic behavior of gravity retaining wall built near rock face", Eartq. Struct., 14(2), 179-186. https://doi.org/10.12989/eas.2018.14.2.179.
  23. Verman, B., Singh, M.N., Viladkar, J.L. and Jethwa, M. (1997), "Effect of tunnel depth on modulus of deformation of rock mass" Rock Mech. Rock Eng., 30(3), 121-127. https://doi.org/10.1007/BF01047388.
  24. Zhang, Y., Ding, X., Huang, S., Qin, Y., Li, P. and Li, Y. (2018), "Field measurement and numerical simulation of excavation damaged zone in a 2000 m-deep cavern", Geomech. Eng., 16(4), 339-413. https://doi.org/10.12989/gae.2018.16.4.399.
  25. Zhao, L.Y., Zhu, Q.Z., Xu, W.Y., Dai, F. and Shao, J.F. (2016), "A unified micromechanics-based damage model for instantaneous and time-dependent behaviors of brittle rocks", Int. J. Rock Mech. Min. Sci., 84, 187-196. https://doi.org/10.1016/j.ijrmms.2016.01.015.

Cited by

  1. Shear failure and mechanical behavior of flawed specimens containing opening and joints vol.23, pp.6, 2020, https://doi.org/10.12989/gae.2020.23.6.587
  2. Deformation modulus of rock foundation in Deriner Arch Dam vol.26, pp.1, 2020, https://doi.org/10.12989/gae.2021.26.1.063