ROCK MASS RATING
RQD - Rock quality designation (RQD) rough is the measure of the degree of jointing or fracture in a rock mass.
Calculation for rock load
An empirical relation obtained between RMR and rock load is : Likely rock load in te/m2 = span in m X mean rock density X ( 1.7 - 0.037 RMR + 0.0002 RMR² )
Support resistance
SR = ( no of bolts X bearing strength of a bolt ) / ( load spacing X gallery width )
safety factor
SF = support resistance / rock load
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