Energy changes accompanying underground mining

Abstract

The discussion in preceding chapters was concerned with the design of single, or mechanically isolated excavations in different types of rock media. In all cases, a design objective was to achieve a static stress distribution, or a set of static forces on discontinuity-defined internal surfaces, which could be sustained by the constituent elements of the rock mass. This approach would be completely satisfactory if the stress concentrations which occur around openings were achieved in a pseudo-static way. In metalliferous mining, the development of mine excavations, for both access and ore production, most frequently involves near-instantaneous generation of segments of the excavation surface. As observed in Chapter 1, the development of an underground opening by removal of supporting rock is mechanically equivalent to application of a set of tractions over a surface representing the excavation boundary. Thus typical excavation development practice is represented mechanically, by the impulsive application of these surface forces in the rock medium.