RMR & GRC

THE PURPOSE
The application can be used as preliminary design tool, allowing user to determine the likely yield or deformation depending on the quality of rock mass (in terms of RMR), tunnel depth and support pressure. The application can also be used to assess the rock mass quality (again in terms of RMR) based on the measured deformation, applied support pressure, depth and tunnel diameter. The following assumptions were made;
- Perfect symmetry under hydrostatic stress loading of circular tunnel,
- No bending moments were induced in the support,
- Rock mass failure characteristic is elastic perfectly plastic
- Dilution angle was zero
- Mechanical properties were isotropic
- The rock mass does not contain joints with a preferred orientation
For more details about assumptions please see References


HOW TO USE MODULE I: CALCULATION OF RMR
Basic RMR is calculated based on the grading of five parameters that are uniaxial compressive strength of rock material, Rock Quality Designation (RQD), Spacing of discontinuities, Ground water conditions. Having basic RMR value the corrected RMR value can also be calculated considering discontinuity orientation.

Enter the parameter values using key board the corresponding grades will automatically be allocated and basic RMR value will be displayed. The calculated RMR value may or may not be used in other modules.


HOW TO USE MODULE II: GRC
Using keyboard enter the values of RMR, tunnel depth and tunnel radius. The regression model will be derived automatically depending on the specified depth. The possible maximum displacement will be calculated and shown together with the ground reaction curve. A chart is also included in the application for rough estimation of support pressures of different support types and elements (tap on `estimates of Support Capacity` bottom).


HOW TO USE MODULE III: BACK ANALYSIS
In this module the possible quality of the rock mass in which the tunnel is excavated can be calculated. Necessary input parameters are tunnel depth, tunnel diameter, tunnel displacement and applied support pressure.


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