Drilling for underground excavation and support in sedimentary rock

It is a well-known fact that the drilling is carried out differently depending on the rock soil conditions. This paper will deal with drilling for blast holes, bolt holes, grout holes and use of support measures like bolting and spiling that are depending on well performed drilling. As there from drilling point of view does not exist a well-defined border between igneous rock and sedimentary rock discussions on the mechanical behaviour of the drilling equipment as well as the response of the rock can be performed in the same way for the two types. This discussion will be held in general terms without any deeper mathematical analysis, and will end up in some general conclusions. A couple of cases on support ahead of the tunnel face will also be given showing the possibility to achieve longer excavation rounds which hopefully will end up in safer cheaper and faster tunnel excavation.