Drilling large underground Tunnels and the modem methods and machines

Abstract

The drilling of large underground tunnels, either for mines or public works, should be approached according to patterns characteristic in all these large projects, which are: safety, strength, economy, etc. Because of the differing techniques and use of the various machines in existence for such an end, the one most advantageous in each case should be chosen. Experience obtained in several years of work and testing teaches us that when the ground is soft, we obtain the best results with the rotary drill; otherwise, it is advisable to use the rotary-percussion drill. Finally, the automatic jumbo has been successfully used, which is very maneuverable and eliminates many of the inconveniences produced by drills, such as: noise, high air consumption and frequent jam-ups. It can be fed with electricity, diesel or diesel-electrical power. It is frequently used, especially in turnpikes.