The quality of the rock mass in which an excavation is being driven has a strong influence on the level of dynamic forces to which the excavation can be subjected and sustain damage. Though each specific rock mass occurrence is unique yet there are common rock mass features which influence the outcome of controlled blasting in a similar way. A field study was conducted which involved assessment of blast damage at several operating mines and the blasting of small-scale models. The effects of block size and strength, joint parameters, ground water, weathering of rocks and rock mass rating on the results of controlled blasting have been investigated and discussed in this study.