ABSTRACT
The use of the underground, for mining as well as for civil engineering projects, requires the driving of drifts and tunnels in a larger number each day. Fragmentation with drilling and blasting solves most of the problems because although the sections are large, the excavations can be carried out in stages with advance drifts, lateral breakage and/or benching, plus the fact that modern jumbos can cover large sections with varying shapes. The remaining rock can be left in good condition with contour blasting using smooth blasting and presplitting techniques which are better adapted to the lithological changes of the ground, and require less machine time, which means the equipment can be sent on to other jobs. The principle behind tunnel blasting is to create an opening by means of a cut and then stoping is carried towards the opening. Stoping can be geometrically compared to bench blasting although it requires powder factors that are 4 to 10 times higher.
