Modern methods to excavate galleries and tunnels

Abstract

The outstanding progress in recent years in the field of public works is basically due to the massive use of machinery at any working site. An obvious example is that of underground excavation, where the progressive use of more advanced machinery has made it possible to attain exceptional performances and reductions in cost. Among the equipment items that have been recently introduced mention should be made of the Jumbos, which are selfpropelled mobile devices, and serve as supporting platforms for the drilling hammers. As the operators are no longer obliged to handle directly the drilling machines, these can now be made much heavier and can attain much higher drilling rates. These devices have a number of features that are directly related to the nature of the work and the cross section to be excavated, but their general design is common to all of them. This article describes some variants of these Jumbos, which have been successfully employed at various working sites in France.