ABSTRACT
This chapter seeks to develop an overall understanding of the main factors that influence the cost of drilling, to lay a foundation upon which the optimization of the drilling and blasting process can be based. It shows how greatly the strength of rock increases with increasing confinement, and particularly how the energy of deformation to fracture increases as we go from uniaxial tension through uniaxial compression to uniaxial strain. These fundamental strength properties of rock materials lead to an interesting and useful relationship between the force; the energy requirement; and the consequent cost for drilling, boring, or blasting on the one hand; and the size of the cavity produced on the other. Mechanical raise boring has largely replaced the conventional drilling and blasting method, and mechanical full-size boring of long tunnels successfully competes with drilling and blasting in all but the hardest rock masses.
