An important objective of the civil and mining engineer concerned with structures in rock such as tunnels, open pits, dam foundations and so forth is the creation of a safe and efficient design. This necessitates an estimate of the immediate and long-term performance of the surface or subsurface opening or foundation, whichever the case may be. This in turn requires a quantitative estimate of those physical and mechanical properties of the rock mass which govern its strength, permeability and deformation charac teristics. To a lesser or greater extent, depending upon the type of engineer ing...