Rock Mass Classification

Rock Mass Classification Calculator (RMR, Q-System, GSI)

Step 1: Rock Mass Rating (RMR)

$$RMR_{basic} = R_1+R_2+R_3+R_4+R_5$$
$$RMR_{89} = RMR_{basic}+R_6$$
$$RMR_{14} = RMR_{89} \times R_7 \times R_8$$

R1 (UCS Rating): R2 (RQD Rating): R3 (Spacing of Discontinuities): R4 (Condition of Discontinuities): R5 (Groundwater Condition): R6 (Orientation of Discontinuities): R7 (Adj. Factor Fc1): R8 (Adj. Factor Fc2):

Step 2: ICE & Fs

$$ICE = \\frac{3704 \\cdot \\sigma_c \\cdot K_o \\cdot e^{(RMR_{89}-100)/24}}{(3-K_o)H} \\cdot F \\cdot K_o$$

σc (UCS, MPa): Ko (Lateral Stress Ratio): H (Tunnel Depth, m): F (Shape Factor): RMR89:

Step 3: Q-System

$$Q = \\frac{RQD}{J_n} \\cdot \\frac{J_r}{J_a} \\cdot \\frac{J_w}{SRF}$$

RQD (%): Jn (Joint Set Number): Jr (Joint Roughness): Ja (Joint Alteration): Jw (Joint Water Reduction): SRF (Stress Reduction Factor):

Step 4: RMR–Q–GSI Correlations

Typical trends from literature:
$$RMR \\approx 9\\ln(Q) + 44$$ (Bieniawski, Barton)
$$GSI \\approx RMR - 5$$
$$\\ln(Q) \\approx 0.22RMR - 1.8$$

Enter RMR (optional): Enter Q (optional):