Geotechnical and Geological Engineering

, Volume 36, Issue 2, pp 905–913 | Cite as

Experimental Study on Failure Characteristics of Schist Under Unloading Condition

  • Hua-yan Yao
  • Shan-po JiaEmail author
  • Hong-guo Li
Original paper


The mechanical properties of rock under unloading condition have significant differences with those under conventional loading condition. To investigate the failure characteristics of schist under complex stress state, uniaxial and trixial compression and unloading confining pressure tests have been carried out on samples in the paper. The results show that the rock samples failed in coupling mode of shear and tension under uniaxial compression, and failed in shear mode under conventional trixial compression. However, the failure modes of the samples can be classified as shear, multiple fracturing, and multiple extension, and the strength of schist is closely related with the failure mode under unloading confining condition. For the unloading condition, the peak strengths of schist samples with shear failure mode are close to those under conventional trixial compression, but the peak strengths with multiple fracturing or multiple extension mode are much higher than those under trixial compression. The internal structure characteristics and stress paths were found to have major influences on the failure modes of schist. Therefore, the failure modes must be considered when the strength characteristics of schist are investigated.


Rock mechanics Trixial compression Unloading confining pressure Failure mode Strength 



The authors gratefully acknowledge the support of the Natural Science Foundation of Hubei Province (Grant No. 2015CFB194), and the Open Research Fund of State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation (Grant No. PLN1507).


  1. Chen WZ, Liu DD, Yang JP, Tan XJ, Wang CG (2008) Power function based Mohr strength criterion for marble with unloading confining pressures. Chin J Rock Mech Eng 27(11):2214–2220 (in Chinese) Google Scholar
  2. He MC, Miao JL, Feng JL (2010) Rock burst process of limestone and its acoustic emission characteristics under ture-triaxial unloading conditions. Int J Rock Mech Min Sci 47:286–298CrossRefGoogle Scholar
  3. Hua AZ, You MQ (2001) Rock failure due to energy release during unloading and application to underground rock burst control. Tunn Undergr Space Technol 16:241–246CrossRefGoogle Scholar
  4. Huang RQ, Huang D (2014) Evolution of rock cracks under unloading condition. Rock Mech Rock Eng 47:453–466CrossRefGoogle Scholar
  5. Huang D, Li YR (2014) Conversion of strain energy in triaxial unloading tests on marble. Int J Rock Mech Min Sci 66:160–168Google Scholar
  6. Huang RQ, Wang XN, Chan LS (2001) Triaxial unloading test of rocks and its implication for rock burst. Bull Eng Geol Environ 60:37–41CrossRefGoogle Scholar
  7. Li TB, Wang LS (1993) An experimental study on the deformation and failure features of a basalt under unloading condition. Chin J Rock Mech Eng 12(4):321–327 (in Chinese) Google Scholar
  8. Li XP, Zhao H, Wang B, Xiao TL (2013) Mechanical properties of deep-buried marble material under loading and unloading tests. J Wuhan Univ Technol 28(3):514–520CrossRefGoogle Scholar
  9. Li XB, Du K, Li DY (2015) True triaxial strength and failure modes of cubic rock specimens with unloading the minor principal stress. Rock Mech Rock Eng 48:2185–2196CrossRefGoogle Scholar
  10. Niu SJ, Jing HW, Liang JQ (2011) Experimental study of failure mode of sandstone under different loading paths. Chin J Rock Mech Eng 30(s2):3966–3974 (in Chinese) Google Scholar
  11. Park CH, Bobet A (2009) Crack coalescence in specimens with open and closed flaws: a comparison. Int J Rock Mech Min Sci 46:819–829CrossRefGoogle Scholar
  12. Sagong M, Bobet A (2002) Coalescence of multiple flaws in a rock-model material in uniaxial compression. Int J Rock Mech Min Sci 39:229–241CrossRefGoogle Scholar
  13. Szwedzicki T (2007) A hypothesis on models of failure of rock samples tested in uniaxial compression. Rock Mech Rock Eng 40(1):97–104CrossRefGoogle Scholar
  14. Szwedzicki T, Shamu W (1999) The effect of material discontinuities on strength of rock samples. In: Proceedings of Australasian Institute of Mining and Metallurgy. 304(1), pp 23–28Google Scholar
  15. Wang RH, Li JL, Liu J, Huang QF (2007) Three-dimensional stability analysis of dam abutment high slope dynamic behaviors considering rock mass unloading. Chin J Rock Mech Eng 26:3515–3521 (in Chinese) Google Scholar
  16. Wu W, Zhao ZH, Duan K (2017) Unloading-induced instability of a simulated granular fault and implications for excavation-induced seismicity. Tunn Undergr Space Technol 63:154–161CrossRefGoogle Scholar
  17. Xiang TB, Feng XT, Chen BR, Jiang Q, Zhang CQ (2009) Rock failure mechanism and true triaxial experimental study of specimens with single structural plane under three-dimensional stress. Rock Soil Mech 30(10):2908–2916 (in Chinese) Google Scholar
  18. You MQ (2002) Destroy character and coulomb criterion of rock specimen in pseudo-triaxial compression. J Geomech 8(2):179–185 (in Chinese) Google Scholar
  19. You MQ, Hua AZ (1998) Triaxial confining depressure test of rock sample. Chin J Rock Mech Eng 17(1):24–29 (in Chinese) Google Scholar
  20. Zhang K, Zhou H, Pan PZ, Shen LF, Feng XT, Zhang YG (2010) Characteristics of strength of rocks under different unloading rates. Rock Soil Mech 31(7):2073–2078 (in Chinese) Google Scholar

Copyright information

© Springer International Publishing AG 2017

Authors and Affiliations

  1. 1.School of Civil EngineeringHefei University of TechnologyHefeiChina
  2. 2.Research Center of Geomechanics and Geotechnical EngineeringYangtze UniversityJingzhouChina

Personalised recommendations