located beside each of the input parameter edit boxes
in the Sidebar.The parameters used as input for the Generalized Hoek-Brown criterion – sigci, mi, GSI and D – can be estimated using convenient charts and tables built into RocData. The modulus ratio (MR) used to estimate the rock deformation modulus can also be estimated.
These charts and tables are accessed by selecting the Pick
button located beside each of the input parameter edit boxes
in the Sidebar.
When you select a Pick button, a table or chart will appear, allowing you to determine a suitable value for the desired parameter. For example, the dialogs for estimation of mi and GSI (Rock Type = General) are shown below.
Dialog for estimation of mi value
Once you have determined a value, select OK in the Pick dialog. The value will be automatically loaded into the Sidebar, and the RocData calculation will automatically be carried out (i.e. output parameters and failure envelopes will be re-calculated using the selected input data).
GSI chart (Rock Type = General)
Notice that there are TWO distinct GSI charts:
One for general rock mass types, and
A second for weak, heterogeneous rock mass types such as flysch, which extends the useful range of GSI down to values as low as 5.
Select the Pick button for each of sigci, mi, GSI and D, and experiment with the dialogs.
For further information about the Hoek-Brown classification parameters sigci, mi, GSI and D, please consult Hoek, Carranza-Torres, Corkum (2002). To view the paper click here.
Modulus Ratio
The Modulus Ratio can be used to estimate the rock deformation modulus. Values of Modulus Ratio can be estimated by selecting the Pick button beside the MR edit box. This will display the following dialog. See the Rock Mass Modulus topic for more information.
Dialog for estimation of Modulus Ratio and intact modulus
