Rock Mass Rating (RMR) Calculator
Calculate Bieniawski RMR classification from UCS, RQD, joint spacing, condition, and groundwater ratings.
Inputs
Results
RMR Score
55
Rock ClassIII
DescriptionFair Rock
Stand-Up Time1 wk for 5 m span
Cohesion Range200-300 kPa
Friction Angle25-35°
How to Use This Calculator
- Enter the UCS Rating (0–15) based on uniaxial compressive strength of intact rock.
- Set the RQD Rating (3–20) from drill core Rock Quality Designation measurements.
- Enter Joint Spacing Rating (5–20) and Joint Condition Rating (0–30) from field mapping.
- Set the Groundwater Rating (0–15) based on observed inflow or pore pressure.
- Review RMR Score, Rock Class (I–V), and Stand-Up Time to design support and excavation sequences.
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