Rock mass rating
Encyclopedia
The rock mass rating system is a geomechanical
classification system for rocks
, developed by Z. T. Bieniawski between 1972 and 1973.
Each of the six parameters is assigned a value corresponding to the characteristics of the rock. These values are derived from field surveys. The sum of the six parameters is the "RMR value", which lies between 0 and 100.
projects such as tunnels, slopes, foundations, and mines. It is also adaptable for knowledge-based expert systems. A joke among engineers is that rock structure can be commonly broken into two general classifications; 'CHILE' — Continuous Homogenous Isotropic Linear Elastic (what most geotechinical engineers would like to see) and 'DIANE' — Discontinuous Inhomogenous Anisotropic Non-Elastic (what most in-situ rock masses actually are). A RMR system provides a method of incorporating some of the complex mechanics of DIANE rocks into engineering design.
Geomechanics
Geomechanics is the geologic study of the behavior of soil and rock. The two main disciplines of geomechanics are soil mechanics and rock mechanics. The former deals with the behaviour of soil from a small scale to a landslide scale...
classification system for rocks
Rock (geology)
In geology, rock or stone is a naturally occurring solid aggregate of minerals and/or mineraloids.The Earth's outer solid layer, the lithosphere, is made of rock. In general rocks are of three types, namely, igneous, sedimentary, and metamorphic...
, developed by Z. T. Bieniawski between 1972 and 1973.
Definition
The following six parameters are used to classify a rock mass using the RMR system- Uniaxial compressive strength of rock material
- Rock quality designation (RQD)
- Spacing of discontinuities
- Condition of discontinuities
- Groundwater conditions
- Orientation of discontinuities
Each of the six parameters is assigned a value corresponding to the characteristics of the rock. These values are derived from field surveys. The sum of the six parameters is the "RMR value", which lies between 0 and 100.
Classification table
Below is the classification table for the RMR system.| RMR | Rock quality |
|---|---|
| 0 - 20 | Very poor |
| 21 - 40 | Poor |
| 41 - 60 | Fair |
| 61 - 80 | Good |
| 81 - 100 | Very good |
Applications
Rock Mass Rating has found wide application in various types of engineeringEngineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
projects such as tunnels, slopes, foundations, and mines. It is also adaptable for knowledge-based expert systems. A joke among engineers is that rock structure can be commonly broken into two general classifications; 'CHILE' — Continuous Homogenous Isotropic Linear Elastic (what most geotechinical engineers would like to see) and 'DIANE' — Discontinuous Inhomogenous Anisotropic Non-Elastic (what most in-situ rock masses actually are). A RMR system provides a method of incorporating some of the complex mechanics of DIANE rocks into engineering design.
Further reading
- Pantelidis L. (2009) "Rock slope stability assessment through rock mass classification systems" International Journal of Rock Mechanics and Mining Sciences, 46(2):315–325.