Abstract
The Geological Strength Index (GSI) is widely used to estimate mechanical parameters of rock mass, but estimation of GSI is relatively subjective because of the lack of quantitative parameters. Hence, the existing method for estimating GSI is not suitable for rock samples from drilled cores. Inspired by the GSI estimation method of flysch (Marinos and Hoke, Proceedings of the GeoEng2000 at the international conference on geotechnical and geological engineering, Melbourne, Technomic publishers, Lancaster, pp 1422–1446, 2000), this paper proposes two parameters, the rock mineral condition and rock core length, for use in a modified, more quantitative method for estimating GSI. This modified method can be used for granite specimens from drilled cores. It uses images of typical core samples instead of the sketches given by Hoek’s GSI estimation method. A modified chart of GSI for granite, which is suitable for estimating mechanical parameters of rock mass from drilled core samples, is then developed. The E (elastic modulus) and Q ult (ultimate bearing capacity) values obtained using our modified method were compared with those from experimental data; the results indicate that the modified method can produce reasonable GSI values and can be used to estimate the mechanical parameters of rock mass from drilled cores.
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References
Barton N (1999) General report concerning some 20th century lessons and 21st century challenges in applied rock mechanics. In: 9th International Congress of Rock Mechanics, Paris, France
Bieniawski ZT (1984) Rock mechanics design in mining and tunneling. Balkema, Rotterdam, p 272
Cai M, Kaiser PK, Uno H, Tasaka Y, Minami M (2004) Estimation of rock mass deformation modulus and strength of jointed hard rock masses using the GSI system. Int J Rock Mech Min Sci 41:3–19
Cai M, Kaiser PK, Tasaka Y, Minami M (2007) Determination of residual strength parameters of jointed rock masses using the GSI system. Int J Rock Mech Min Sci 44(2):247–265
Hoek E, Brown ET (1980) Empirical strength criterion for rock masses. J Geotech Eng Div ASCE 106(GT9):1013–1035
Hoek E, Brown ET (1997) Practical estimates of rock mass strength. Int J Rock Mech Min Sci 34(8):1165–1186
Hoek E, Marinos P, Benissi M (1998) Applicability of the geological strength index (GSI) classification for very weak and sheared rock masses: The case of the Athens Schist Formation. Bull Eng Geol Environ 57(2):151–160 (Example no. 3)
Hoek E, Carlos C, Corkum B (2002) Hoek–Brown failure criterion—2002 edition. Proceedings of 5th North American Rock Mechanics Symposium. Toronto, 267–273
Hoseinie SH, Aghababaei H, Pourrahimian Y (2008) Development of a new classification system for assessing of Rock mass Drillability index (RDi). Int J Rock Mech Min Sci 45:1–10
Li P-Y, Yang Q, Luan M-T (2005) Modification of formula estimating ultimate bearing capacity of rock foundation based on Hoek-Brown strength criterion. Rock Soil Mech 26(4):64–666
Lin D (2012) Study on rock mass structure and geophysics features for granite in shallow—take CSNS for example. GUCAS pp 31–39 (in Chinese)
Lin D, Shang Y, Wu F et al (2011) Study of geological strength index for granite based on mineral structure and drilling and its application. Chin J Rock Mech Eng 30(4):761–768 (in Chinese)
Lu F-X, Song L-K (2002) Petrology[M]. Geological press, Beijing (in Chinese)
Marinos P, Hoek E (2000) GSI: a geologically friendly tool for rock mass strength estimation. In: Proceedings of the GeoEng2000 at the international conference on geotechnical and geological engineering, Melbourne, Technomic publishers, Lancaster, pp 1422–1446
Palmstrom A (1996) Characterizing rock masses by the RMi for use in practical rock engineering. Tunnel Underg Space Technol 11(2):175–188
Reza Osgoui, Ünal Erdal (2009) An empirical method for design of grouted bolts in rock tunnels based on the Geological Strength Index (GSI). Eng Geol 107(3–4):154–166
Russo G (2009) A new rational method for calculating the GSI. Tunnel Undergr Space Technol 24:103–111
Singh JL, NK Tamrakar (2013) Rock Mass Rating and Geological Strength Index of rock masses of Thopal-Malekhu River areas, Central Nepal Lesser Himalaya. Bull Dep Geol
Song J-B, Yu Y-Z (2002) Bell solution determining ultimate bearing capacity of homogeneous rock foundation under shear failure model. Chin J Rock Mech Eng 21(3):410–412 (in chinese)
Sonmez H, Ulusay R (1999) Modifications to the geological strength index (GSI) and their applicability to stability of slopes. Int J Rock Mech Min Sci 36:743–760
Su Y, Feng L, Li Z, Zhao M (2009) Quantification of elements for geological strength index in Hoek-Brown Criterion. Chin J Rock Mech Eng 28(4):679–687 (In chinese)
Sun GZ (2011) Mechanics of rock mass structure. Science press, 101–120 (in Chinese)
Wyllie DC (1992) Foundations on rock. E & FN Spon, London
Acknowledgments
This study was supported by National Natural Science Foundation of China (Grant No. 41302254), Chinese Special Funds for Major State Basic Research Project (Grant No. 2010CB732001). We would like to express our deep appreciation to Minghua Zhang from Institute of Shaoguan geological survey for supplying test results, to the editor and reviewers for their helpful comments and suggestion.
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Lin, D., Sun, Y., Zhang, W. et al. Modifications to the GSI for granite in drilling. Bull Eng Geol Environ 73, 1245–1258 (2014). https://doi.org/10.1007/s10064-014-0581-0
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DOI: https://doi.org/10.1007/s10064-014-0581-0