Discrete element analysis for mined tunnels in statistically homogenous jointed rock masses indicate that the volume loss at different levels (above tunnel crown) is almost constant and unique for a given tunnel and the ground settlement profile of mined rock tunnels can be reasonably estimated with inverted Gaussian normal distribution.With special reference to the volume loss, a rock mass classification system, i.e.IMRT(Index of Mined Rock Tunnels) which is similar to Bieniawskis RMR89,has been proposed based on extensive parametric study of the rock block and joint properties.According to the extensive numerical analysis,correlation between the ground volume loss and IMRT is established and thus ground settlement of mined rock tunnels can be reasonably predicted.