Indian Rock mass rating system designed by CMRI-ISM. In this system, following five parameters were used to classify Rock mass for designing support system in underground Coal Mines. Each of the parameter is assigned a value corresponding to the characteristics of Rock. These are derived from Field serveys and laboratory tests. The sum of five the parameter is 'RMR value' which lies between 0 to 100.
Parameter Max. Rating
Layer thickness 30
Structural feature 25
Weatherability 20
Rock strength 15
Ground water 10
_______
Total 100
Classification of Roof Rock according to RMR SYSTEM :
RMR value Rock Quality
0-20 Very Poor
21-40 Poor
41- 60 Fair
61-80 Good
81-100 Very Good
Comments