Improvement of the concept of the blockiness level of rock masses

Abstract

The concept of blockiness level, which enables the measurement of the jointing degree of rock mass in three dimensions, is limited due to some significant shortcomings. In this study, to tackle the limitations, the guidelines for the applications of the concept were formulated according to the calculation basis of blockiness level. Then, a more reasonable computational method of the blockiness level was proposed, the ratings for the blockiness levels and corresponding jointing degrees of rock mass were modified, and the improved concept of the blockiness level was validated and supported through the artificial data. Finally, the improved concept was applied to two real cases, i.e., the Wudongde Hydropower Project (China) and the underground powerhouse of the Three Gorges Project (China). Different discontinuity network models, which were generated by deterministic discontinuities and following the Discrete Fracture Network approach, respectively, were presented in the two case studies, and the results show that the blockiness levels of the two adits (i.e., PD49-1 and PD 4) in Wudongde Hydropower Project are 12.847% and 10.168%, respectively, both belonging to the relatively integrated category, and the blockiness level of the underground powerhouse of the Three Gorges Project is 3.6‰, falling into the integrated category. The improved concept of the blockiness level was found to be acceptable and practicable.

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References

  1. Agliardi F, Crosta GB, Meloni F, Valle C, Rivolta C (2013) Structurally-controlled instability, damage and slope failure in a porphyry rock mass. Tectonophysics 605(605):34–47. https://doi.org/10.1016/j.tecto.2013.05.033

    Article  Google Scholar 

  2. Bar N, Barton N (2017) The Q-slope method for rock slope engineering. Rock Mech Rock Eng 50(12):3307–3322. https://doi.org/10.1007/s00603-017-1305-0

    Article  Google Scholar 

  3. Bieniawski ZT (1973) Engineering classification of jointed rock masses. Civ Eng S Afr 15:335–343

    Google Scholar 

  4. Celada B, Tardáguila I, Varona P, Bieniawski ZT (2014) Innovating tunnel design by an improved experience-based RMR system, vol 3. Proceedings of the World Tunnel Congress 2014 – Tunnels for a Better Life, Foz do Iguaçu, Brazil, pp 1–9

  5. Chen DJ, Liu TH (1979) A new index of rock mass quality evaluation: blockiness modulus. Selected papers of the first Chinese Engineering Geology Academic Conference. Engineering Geology Committee of Geological Society of China: Editorial Department of Engineering Geology Journal

  6. Chen QF, Wei CS, Niu WJ, Chen DY, Feng CH, Fan Q (2014) Stability classification of roadway roof in fractured rock mass based on blockiness theory. Rock Soil Mech 35(10):2901–2908. https://doi.org/10.16285/j.rsm.2014.10.026

    Article  Google Scholar 

  7. Chen QF, Niu WJ, Huang RG, Fan QY, Chen JG (2015) Roof stability classification method based on blockiness and the matter-element extension theory and its application. Chin J Eng 37(12):1550–1556. https://doi.org/10.13374/j.issn2095-9389.2015.12.003

    Article  Google Scholar 

  8. Choi SY, Park HD (2004) Variation of rock quality designation (RQD) with scanline orientation and length: a case study in Korea. Int J Rock Mech Min Sci 41(2):207–221. https://doi.org/10.1016/S1365-1609(03)00091-1

    Article  Google Scholar 

  9. Deere DU (1989) Rock Quality Designation (RQD) After Twenty Years. Contract Report GL-89-1. https://doi.org/10.1016/B978-0-12-385878-8.00004-5.

  10. Department of hydraulic power of the People’s Republic of China (2008) Code for engineering geological investigation of water resources and hydropower. Water Resources and Electric Power Press (China)

  11. Du S, Wang S (1996) Simple analysis of anisotropy of rock quality designation. J Eng Geol 4(4):48–54

    Google Scholar 

  12. Guo Q, Ge X, Che A (2011) Research on relationship of rock mass integrity index and rock mass elastic modulus. Chin J Rock Mech Eng 30(2):3914–3919

    Google Scholar 

  13. Hoek E, Diederichs MS (2013). “Quantification of the Geological Strength Index Chart.” 47th US Rock Mechanics / Geomechanics Symposium Held in San Francisco, CA, USA June 23-26, 2013, 9.

  14. ISRM (1978) Suggested methods for the quantitative description of discontinuities in rock masses. Int J Rock Mech Min Sci 15(6):319–368. https://doi.org/10.1016/0148-9062(79)91476-1

    Article  Google Scholar 

  15. Kim BH, Cai M, Kaiser PK, Yang HS (2007) Estimation of block sizes for rock masses with non-persistent joints. Rock Mech Rock Eng 40(2):169–192. https://doi.org/10.1007/s00603-006-0093-8

    Article  Google Scholar 

  16. Lin F (2008) Evaluation of in-situ measurement methods for counting volumetric joints of rock mass. J Eng Geol 16:663–666. https://doi.org/10.1016/S1872-5791(08)60058-5

    Article  Google Scholar 

  17. Liu XF (2010). “Studies on blockiness of fractured rock mass. Dissertation.” China University of Geosciences (Beijing), China.

  18. Liu Q, Liu J, Pan Y, Kong X, Hong K (2017) A case study of TBM performance prediction using a Chinese rock mass classification system – hydropower classification (HC) method. Tunn Undergr Sp Tech 65:140–154. https://doi.org/10.1016/j.tust.2017.03.002

    Article  Google Scholar 

  19. Ma CF, Li X, Cheng GW, Pu CL (2010) Study of practical approach to assess integrality of engineering rock mass. Rock Soil Mech 31(11):3579–3584. https://doi.org/10.16285/j.rsm.2010.11.029

    Article  Google Scholar 

  20. Ministry of construction of the People’s Republic of China (1995) PRC National Standard. Standard for engineering classification of rock masses. China Planning Press

  21. Ministry of construction of the People’s Republic of China (2002) Code for investigation of geotechnical engineering. China planning press

  22. Palmstrom A (1982). The volumetric joint count: a useful and simple measure of the degree of rock mass jointing. Proc. of the 4th Congr. Int. Assoc, of Engng. Geology, 2: 221–228.

  23. Palmstrom A (2005) Measurements of and correlations between block size and rock quality designation (RQD). Tunn Undergr Sp Tech 20(4):362–377. https://doi.org/10.1016/j.tust.2005.01.005

    Article  Google Scholar 

  24. Pells PJ, Bieniawski ZT, Hencher SR, Pells SE (2017) Rock quality designation (RQD): time to rest in peace. Can Geotech J 54:825–834. https://doi.org/10.1139/cgj-2016-0012

    Article  Google Scholar 

  25. Riquelme AJ, Abellán A, Tomás R (2015) Discontinuity spacing analysis in rock masses using 3D point clouds. Eng Geol 195:185–195. https://doi.org/10.1016/j.enggeo.2015.06.009

    Article  Google Scholar 

  26. Riquelme AJ, Tomás R, Abellán A (2016) Characterization of rock slopes through slope mass rating using 3D point clouds. In J Rock Mech Min Sci 84:165–176. https://doi.org/10.1016/j.ijrmms.2015.12.008

    Article  Google Scholar 

  27. Wang XM (2013) Study on rock fractures and rock blocks in Wudongde dam area. PhD Thesis, China University of Geosciences (Beijing), China.

  28. Wang CY, PeiLiang HU, Sun WC (2010) Method for evaluating rock mass integrity based on borehole camera technology. Rock Soil Mech 32(4):1326–1330. https://doi.org/10.16285/j.rsm.2010.04.008

    Article  Google Scholar 

  29. Weiss M (2008) Techniques for estimating fracture size: a comparison of methods. Int J Rock Mech Min Sci 45(3):460–466. https://doi.org/10.1016/j.ijrmms.2007.07.010

    Article  Google Scholar 

  30. Xia L, Li M, Chen Y, Zheng Y, Yu Q (2015) Blockiness level of rock mass around underground powerhouse of Three Gorges Project. Tunn Undergr Sp Tech 48:67–76. https://doi.org/10.1016/j.tust.2015.02.002

    Article  Google Scholar 

  31. Xia L, Zheng Y, Yu Q (2016) Estimation of the REV size for blockiness of fractured rock masses. Comput Geotech 76:83–92. https://doi.org/10.1016/j.compgeo

    Article  Google Scholar 

  32. Yu Q, Ohnishi Y, Xue G, Chen D (2009) A generalized procedure to identify three-dimensional rock blocks around complex excavations. Int J Nume Anal Met 33(3):355–375. https://doi.org/10.1002/nag.720

    Article  Google Scholar 

  33. Zhang Q, Bian Z, Yu M (2009) Preliminary research on rockmass integrity using spatial block identification technique. Chin J Rock Mech Eng 28(3):507–515. https://doi.org/10.1007/978-3-540-85168-4_52

    Article  Google Scholar 

  34. Zhang W, Chen J, Cao Z, Wang R (2013) Size effect of RQD and generalized representative volume elements: a case study on an underground excavation in Baihetan dam, Southwest China. Tunn Undergr Sp Tech 35:89–98. https://doi.org/10.1016/j.tust.2012.12.007

    Article  Google Scholar 

Download references

Funding

This work was financially supported by the General Project of Guangxi Natural Science Foundation (Grant No. 2019GXNSFAA185026).

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Contributions

All authors contributed to the study conception and design. Material preparation, data collection, and analysis were performed by Qingfa Chen, Shaoping Wang, Tingchang Yin, and Wenjing Niu. The first draft of the manuscript was written by Qingfa Chen and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

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Correspondence to Qingfa Chen.

Additional information

Responsible Editor: Zeynal Abiddin Erguler

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Cite this article

Chen, Q., Wang, S., Yin, T. et al. Improvement of the concept of the blockiness level of rock masses. Arab J Geosci 14, 84 (2021). https://doi.org/10.1007/s12517-020-06374-8

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Keywords

  • Fractured rock mass
  • Blockiness level
  • Block percentage
  • Jointing degree of rock mass
  • Three-dimensional measurement