Geomechanics and Engineering

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Strength degradation of a natural thin-bedded rock mass subjected to water immersion and its impact on tunnel stability

  • Zhang, Yuting (Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Changjiang River Scientific Research Institute) ;
  • Ding, Xiuli (Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Changjiang River Scientific Research Institute) ;
  • Huang, Shuling (Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Changjiang River Scientific Research Institute) ;
  • Wu, Yongjin (Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Changjiang River Scientific Research Institute) ;
  • He, Jun (Key Laboratory of Geotechnical Mechanics and Engineering of the Ministry of Water Resources, Changjiang River Scientific Research Institute)
  • Received : 2020.01.17
  • Accepted : 2020.03.10
  • Published : 2020.04.10
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Abstract

Strength anisotropy is a typical feature of thin-bedded rock masses and their strength will be degraded subjected to water immersion effect. Such effect is crucial for the operation of hydropower plant because the impoundment lifts the water level of upstream reservoir and causes the rock mass of nearby slopes saturated. So far, researches regarding mechanical property of natural thin-bedded rock masses and their strength variation under water immersion based on field test method are rarely reported. This paper focuses on a thin-bedded stratified rock mass and carries out field test to investigate the mechanical property and strength variation characteristics. The field test is highlighted by samples which have a large shear dimension of 0.5 m*0.5 m, representing a more realistic in-situ situation than small size specimen. The test results confirm the anisotropic nature of the concerned rock mass, whose shear strength of host rocks is significantly larger than that of bedding planes. Further, the comparison of shear strength parameters of the thin-bedded rock mass under natural and saturated conditions show that for both host rocks and bedding planes, the decreasing extent of cohesion values are larger than friction values. The quantitative results are then adopted to analyze the influence of reservoir impoundment of a hydropower plant on the surrounding rock mass stability of diversion tunnels which are located in the nearby slope bank. It is evaluated that after reservoir impoundment, the strength degradation induced incremental deformations of surrounding rock mass of diversion tunnels are small and the stresses in lining structure are acceptable. It is therefore concluded that the influences of impoundment are small and the stability of diversion tunnels can be still achieved. The finings regarding field test method and its results, as well as the numerical evaluation conclusions are hoped to provide references for rock projects with similar concerns.

Keywords

Acknowledgement

Supported by : National Natural Science Foundation of China, Central Research Institutes of Public Causes

The work was supported by the National Natural Science Foundation of China (Nos. 51539002 and 51779018) and the Basic Research Fund for Central Research Institutes of Public Causes (Nos. CKSF2019434/YT and CKSF2019169/YT)

References

  1. Alemdag, S., Gurocak, Z., Cevik, A., Cabalar, A.F. and Gokceoglu, C. (2016), "Modeling deformation modulus of a stratified sedimentary rock mass using neural network, fuzzy inference and genetic programming", Eng. Geol., 203, 70-82. https://doi.org/10.1016/j.enggeo.2015.12.002.
  2. Aydan, O., Ulusay, R. and Tokashiki, N (2014), "A new rock mass quality rating system: rock mass quality rating (RMQR) and its application to the estimation of geomechanical characteristics of rock masses", Rock Mech. Rock Eng., 47(4), 1255-1276. https://doi.org/10.1007/s00603-013-0462-z.
  3. Ding, X., Weng, Y., Zhang, Y., Xu, T., Wang, T., Rao, Z. and Qi, Z. (2017), "Stability of large parallel tunnels excavated in weak rocks: A case study", Rock Mech. Rock Eng., 50(9), 2443-2464. https://doi.org/10.1007/s00603-017-1247-6.
  4. Fortsakis, P., Nikas, K., Marinos, V. and Marinos, P. (2012), "Anisotropic behaviour of stratified rock masses in tunnelling", Eng. Geol., 141, 74-83. https://doi.org/10.1016/j.enggeo.2012.05.001.
  5. Gokceoglu, C. and Aksoy, H. (2000), "New approaches to the characterization of clay-bearing, densely jointed and weak rock masses", Eng. Geol., 58(1), 1-23. https://doi.org/10.1016/S0013-7952(00)00032-6.
  6. Gu, H., Tao, M., Wang, J., Jiang, H., Li, Q. and Wang, W. (2018), "Influence of water content on dynamic mechanical properties of coal", Geomech. Eng., 16(1), 85-95. https://doi.org/10.12989/gae.2018.16.1.085.
  7. Hoek, E., Marinos, P.G. and Marinos, V.P. (2005), "Characterisation and engineering properties of tectonically undisturbed but lithologically varied sedimentary rock masses", Int. J. Rock Mech. Min. Sci., 42(2), 277-285. https://doi.org/10.1016/j.ijrmms.2004.09.015.
  8. Ishida, T., Kanagawa, T. and Kanaori, Y. (2010), "Source distribution of acoustic emissions during an in-situ direct shear test: Implications for an analog model of seismogenic faulting in an inhomogeneous rock mass", Eng. Geol., 110(3-4), 66-76. https://doi.org/10.1016/j.enggeo.2009.11.003.
  9. Kim, E. and Changani, H. (2016), "Effect of water saturation and loading rate on the mechanical properties of Red and Buff Sandstones", Int. J. Rock Mech. Min. Sci., (88), 23-28. http://dx.doi.org/10.1016%2Fj.ijrmms.2016.07.005.
  10. Kundu, J., Mahanta, B., Sarkar, K. and Singh, T.N. (2018), "The effect of lineation on anisotropy in dry and saturated Himalayan Schistose Rock under Brazilian test conditions", Rock Mech. Rock Eng., 51(1), 5-21. https://doi.org/10.1007/s00603-017-1300-1305.
  11. Liu, K. and Sheng, J.J. (2019), "Experimental study of the effect of stress anisotropy on fracture propagation in Eagle Ford shale under water imbibition", Eng. Geol., 249, 13-22. https://doi.org/10.1016/j.enggeo.2018.12.023.
  12. Liu, X., Liu, Q., Liu, B., Zhu, Y. and Zhang, P. (2019), "Failure behavior for rocklike material with cross crack under biaxial compression", J. Mater. Civ. Eng., 31(2), 06018025. https://doi.org/10.1061/(ASCE)MT.1943-5533.0002540.
  13. Marinos, V. (2019), "A revised, geotechnical classification GSI system for tectonically disturbed heterogeneous rock masses, such as flysch", Bull. Eng. Geol. Environ., 78(2), 899-912. https://doi.org/10.1007/s10064-017-1151-z.
  14. 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(2), 115-131. https://doi.org/10.1016/S0886-7798(01)00038-4.
  15. Pellet, F.L., Keshavarz, M. and Boulon, M. (2013), "Influence of humidity conditions on shear strength of clay rock discontinuities", Eng. Geol., 157, 33-38. https://doi.org/10.1016/j.enggeo.2013.02.002.
  16. Roy, D.G., Singh, T.N., Kodikara, J. and Das, R. (2017), "Effect of water saturation on the fracture and mechanical properties of sedimentary rocks", Rock Mech. Rock Eng., 50(10), 2585-2600. https://doi.org/10.1007/s00603-017-1253-8.
  17. Tang, S.B., Yu, C.Y., Heap, M.J., Chen, P.Z. and Ren, Y.G. (2018), "The influence of water saturation on the short-and long-term mechanical behavior of red sandstone", Rock Mech. Rock Eng., 51(9), 2669-2687. https://doi.org/10.1007/s00603-018-1492-3.
  18. The Specification Compilation Group of the Ministry of Water Resources of the People's Republic of China (2001), Specification for Rock Tests in Water Conservancy and Hydroelectric Engineering(SL264-2001), China Water and Power Press, Beijing, China.
  19. Umrao, R.K., Sharma, L.K., Singh, R. and Singh, T.N. (2018), "Determination of strength and modulus of elasticity of heterogenous sedimentary rocks: An ANFIS predictive technique", Measurement, 126, 194-201. https://doi.org/10.1016/j.measurement.2018.05.064.
  20. Xing, H., Liu, L. and Luo, Y. (2019), "Water-induced changes in mechanical parameters of soil-rock mixture and their effect on talus slope stability", Geomech. Eng., 18(4), 353-362. https://doi.org/10.12989/gae.2019.18.4.353.
  21. Zhang, F., Cui, Y., Zeng, L., Robinet, J.C., Conil, N. and Talandier, J. (2018), "Effect of degree of saturation on the unconfined compressive strength of natural stiff clays with consideration of air entry value", Eng. Geol., 237, 140-148. https://doi.org/10.1016/j.enggeo.2018.02.013.
  22. Zhao, Y., Liu, S., Jiang, Y., Wang, K. and Huang, Y. (2016), "Dynamic tensile strength of coal under dry and saturated conditions", Rock Mech. Rock Eng., 49(5), 1709-1720. https://doi.org/10.1007/s00603-015-0849-0.
  23. Zhao, Z., Yang, J., Zhou, D. and Chen, Y. (2017), "Experimental investigation on the wetting-induced weakening of sandstone joints", Eng. Geol., 225, 61-67. https://doi.org/10.1016/j.enggeo.2017.04.008.
  24. Zhou, Z., Cai, X., Cao, W., Li, X. and Xiong, C. (2016), "Influence of water content on mechanical properties of rock in both saturation and drying processes", Rock Mech. Rock Eng., 49(8), 3009-3025. https://doi.org/10.1007/s00603-016-0987-z.

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