Civil Engineering Reference
In-Depth Information
Many predictive models for estimation of rock mass modulus and other rock me-
chanical parameters in consideration of scale effects are based on empirical classi-
fication systems assuming discontinuity systems with randomly distributed orien-
tations (Bieniawski 1978, Serafim & Pereira 1983, Nicholson & Bieniawski 1990,
Hoek & Brown 1997, Read et al. 1999, Palmström & Singh 2001, Barton 2002,
Hoek et al. 2002, Gokceoglu et al. 2003, Kayabasi et al. 2003, Sonmez et al. 2004,
Hoek & Diederichs 2006, Sonmez et al. 2006). However, in our experience, these
cannot be considered reliable for jointed rock (Chapter 12).
Other approaches based on probabilistic and statistical procedures such as Weibull's
weakest-link theory of the strength of materials (Weibull 1939) are not very suitable for
engineering practice and in addition in most cases are not applicable due to lack of suf-
ficient data (Yegulalp & Tahtab 1983, Charrua-Graca 1987, Zhang & Valliappan 1991,
Yegulalp & Kim 1992, Kim & Gao 1995).
Thus, testing, monitoring, back analyses, experience and engineering judgement are
components of an all-embracing procedure for evaluating rock mechanical parameters.
An example for this procedure was outlined in Section 8.6. Further examples will be
presented in Chapters 19, 20, 22, 24 and 25.
18.2
Examples
The rock mechanical parameters of different rock masses are compiled in Tables 18.1
to 18.25. These parameters have been evaluated by WBI for several decades. In these
tables, where available, a structural model, a photo, the elastic constants, the strength
of the intact rock, the strength of discontinuities and the permeability of the respec-
tive rock mass are presented. When ranges of scatter are specified, they do not include
locally appearing maximum values. Otherwise the given values represent the order of
magnitude of characteristic parameters and are there to serve as an aid to evaluate rock
mechanical parameters in practical cases.
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