What Is the Bieniawski Rock Mass Rating (RMR89) Classification Calculator?
Bieniawski's RMR89 system is the international empirical standard for assessing underground rock quality, tunnel support guidelines, and roof span stability.
How Does the Bieniawski Rock Mass Rating (RMR89) Classification Calculator Work?
The calculation evaluates user-provided measurements using recognized domain equations, converts between measurement units, and adjusts for real-world efficiency factors.
Bieniawski Rock Mass Rating (RMR89) Classification Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
Final RMR scores from 0 to 100 categorize rock from Class V (Very Poor, RMR < 21) up to Class I (Very Good, RMR > 80).
How to Use the Bieniawski Rock Mass Rating (RMR89) Classification Calculator
- Enter your primary measurements in the input fields above.
- Select your preferred units (e.g. metric or imperial) if applicable.
- Review or adjust operational assumptions such as field efficiency.
- Click Calculate to instantly generate the full results breakdown and visual chart.
- Use the Reset button at any time to clear the form and test a new scenario.
Step-by-Step Example Calculation
Class II Good Rock Tunnel Profile
Input Values:
Understanding Your Result
Your calculated result represents the realistic operational capacity or baseline output under the specified conditions. Comparing theoretical and effective outputs reveals the direct impact of turns, overlap, and practical downtime.
Factors That Affect the Result
Field terrain, operator experience, equipment maintenance, overlap margin, and weather conditions can significantly influence real-world output.
When Should You Use This Calculator?
Use this calculator whenever you need quick, verified estimates for job planning, budgeting, equipment sizing, or project timelines.
Assumptions & Limitations
- Orientation adjustment depends on strike and dip alignment relative to tunnel axis drive direction.
Frequently Asked Questions
Calculation Accuracy & Reference Note
This calculator implements verified, deterministic mathematical equations based on published standards. Results should be treated as professional engineering estimates; always verify critical operations with local equipment manuals and site inspections.