Determine from lab UCS test, point load index (PLI × 24 ≈ UCS), or Schmidt hammer correlation.
RQD = sum of core pieces >100 mm ÷ total core run × 100. No core? Use RQD = 115 − 3.3 × Jv (Palmstrom 1982).
Average distance between the dominant discontinuity set (joints, bedding planes, or faults).
Rate all five sub-parameters separately. Total is automatically capped at 30.
Observe at tunnel face or borehole. Rate conservatively — seasonal variation often means wetter than initial observations.
How joint orientation affects your excavation type. Adverse orientations can subtract up to 12 points (tunnel) or 60 points (slope).
This is what makes RMR14 different from RMR89. EQA accounts for how the excavation method disturbs the rock mass. TBM boring is least disruptive (EQA = 15); poor blasting is most damaging (EQA ≈ 0). This raises the maximum possible RMR score from 100 to 115.
TBM = 15 · Roadheader = 12–14 · Smooth blast = 10–12 · Controlled blast = 8–10 · Conventional blast = 4–8 · Poor blast = 0–4
Based on Bieniawski 2014 RMR classification for your inputs below.
| ① UCS Rating | — |
| ② RQD Rating | — |
| ③ Spacing Rating | — |
| ④ Discontinuity Condition (max 30) | — |
| ⑤ Groundwater Rating | — |
| ⑥ Orientation Adjustment | — |
| Basic RMR (pre-EQA) | — |
| ★ EQA Adjustment | — |
| Total RMR14 Score | — |
| GSI Estimate (≈ Basic RMR − 5) | — |
| Approx. Q-System (from RMR correlation) | — |
| Rock Mass Deformation Modulus (Em) | — |
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Need RMR89 or other rock classification tools?
Visit our full calculator suite — RMR89, Q-System, GSI, SMR and more.
RMR89 vs RMR14 — Key Differences
What changed in the 2014 update and when to use each version.
| Feature | RMR89 (Bieniawski 1989) | RMR14 (Bieniawski 2014) |
|---|---|---|
| Base parameters | 6 parameters | Same 6 + EQA factor |
| Maximum score | 100 | 115 (EQA adds up to 15) |
| Excavation method | Not considered | ✓ EQA accounts for it |
| TBM accuracy | Underestimates performance | Corrected — TBM gets EQA = 15 |
| Poor blasting | Overestimates rock quality | EQA penalty reduces score |
| Best for | Preliminary studies, slope analysis | Modern tunnels, TBM, final design |
| GSI correlation | GSI ≈ RMR89 − 5 | Apply to base RMR (before EQA) |
| Q-System link | RMR ≈ 9 ln(Q) + 44 | Use base RMR for this correlation |
Also need the RMR89 Calculator?
Our main site has a dedicated RMR89 tool with full classification and support tables.
RMR14 Rock Mass Classification Table
Bieniawski 2014 — five classes of rock mass quality. Maximum score with EQA is 115.
| Class | RMR14 Score | Description | Stand-up Time | Cohesion | Friction Angle |
|---|---|---|---|---|---|
| I | 81–115 | Very Good Rock | 20 yrs / 15 m span | > 400 kPa | > 45° |
| II | 61–80 | Good Rock | 1 yr / 10 m span | 300–400 kPa | 35–45° |
| III | 41–60 | Fair Rock | 1 week / 5 m span | 200–300 kPa | 25–35° |
| IV | 21–40 | Poor Rock | 10 hrs / 2.5 m span | 100–200 kPa | 15–25° |
| V | ≤ 20 | Very Poor Rock | 30 min / 1 m span | < 100 kPa | < 15° |
Tunnel Support Recommendations by Rock Class
Primary support guidelines based on Bieniawski 2014 RMR classification.
Class I — Very Good Rock (81–115)
Generally self-supporting. Spot rock bolts only where required. Shotcrete normally not needed. Minimal monitoring required.
Class II — Good Rock (61–80)
Spot rock bolts 3 m long at 2.5 m spacing in crown. 50 mm shotcrete in crown where required.
Class III — Fair Rock (41–60)
Systematic 4 m bolts at 1.5–2 m spacing. Shotcrete 50–100 mm in crown and walls. Wire mesh in crown.
Class IV — Poor Rock (21–40)
4–5 m bolts at 1–1.5 m spacing. Shotcrete 100–150 mm. Medium steel ribs at 0.75 m spacing.
Class V — Very Poor Rock (≤ 20)
Immediate face bolting. Heavy steel ribs at 0.5 m spacing. Forepoling, grouting, and closed invert often required.
What is RMR14? Complete Guide
Everything engineers and students need to know about the Bieniawski 2014 Rock Mass Rating system.
The RMR14 Formula
RMR14 = UCS + RQD + Spacing + Condition + Groundwater + Orientation + EQA
The first six parameters are identical to RMR89. The EQA (0–15) raises the maximum score from 100 to 115. A higher EQA means less rock damage from excavation.
Why RMR14 Was Developed
After 25 years of RMR89 use, it was recognised that excavation method significantly affects actual rock mass behaviour — yet RMR89 ignored it. A TBM-bored tunnel performs very differently from the same rock mass excavated with poor blasting. Bieniawski 2014 corrects this critical gap.
EQA Score Reference
- TBM (full-face boring): EQA = 15
- Roadheader / mechanical: EQA = 12–14
- Smooth / presplit blasting: EQA = 10–12
- Controlled drill & blast: EQA = 8–10
- Conventional blast: EQA = 4–8
- Poor blasting (>0.5 m overbreak): EQA = 0–4
When to Use RMR14
- TBM-driven tunnels (metro, road, rail)
- Projects with varying excavation quality
- Final support design (not just preliminary)
- Overbreak control is critical
- Comparing excavation method options
- Modern underground infrastructure projects
Top Mistakes to Avoid
- Applying EQA before excavation takes place
- Using the same EQA across different blast quality zones
- Rating groundwater conditions too optimistically
- Averaging RQD across different rock units — classify each zone separately
- Forgetting the orientation adjustment — can subtract up to 12 points
RMR14 and GSI / Q-System
GSI estimate: GSI ≈ RMR89base − 5 (using the RMR score before EQA).
Q-System correlation: RMR ≈ 9 ln(Q) + 44 also uses base RMR. Always run both systems and compare — significant divergence signals unusual site conditions requiring investigation.
Related Rock Classification Tools
Use these alongside RMR14 for a complete geotechnical picture. All available on rockmassratingcalculator.com.
Frequently Asked Questions about RMR14
Common questions from engineers, students, and site professionals.
| Basic RMR (pre-EQA) | — |
| EQA Adjustment | — |
| Total RMR14 | — |
| Rock Class | — |
| Stand-up Time | — |
| GSI Estimate | — |
Implements Bieniawski 2014. Verify with a qualified geotechnical engineer for final design.