Geology Reference
In-Depth Information
Figure 10.14
Specimen calculation showing workings for Hoek Brown param-
eters, rock mass compressive and tensile strength.
more on descriptive observations. For better quality rock masses (for example,
RMR
25), the GSI can be estimated directly from the RMR. An inherent
source of uncertainty with the RMR system is that up to 15% of the rating can
be attributed to ground water conditions, which can change on the scale of hours
or less from dry to wet due simply to localised rainfall. The GSI system does
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