ABSTRACT:
The fragmentation behaviour of a rock mass subjected to block caving is affected by the strength of the intact rock, the orientation, continuity, spacing and strength of the discontinuities and the insitu stress. Combined finite element/discrete element models are suitable for simulating such rock engineering problems that are predominantly characterised by a transformation from a continuous to a discontinuous state. A computational strategy based on the methodology has been incorporated within the Elfen code and its application is illustrated by the simulation of typical block caving operations that involve several distinct fracture and flow phenomena.
1 INTRODUCTION
Block caving is becoming an increasingly important mining method for rock masses that were previously considered to be too strong, located at greater than usual depth or as an extension of open pit mining. The behaviour of the rock mass is affected by the strength of the intact rock, the orientation, continuity, spacing and strength of the discontinuities and the in-situ stress. Combined finite element/discrete element models are suitable for simulating rock engineering problems, such as block caving, that are characterised by a transformation from a continuous to a discontinuous state. The problems are initially represented by a relatively small number of discrete regions within the rock mass to be caved. During the operational phase the material is progressively damaged and the subsequent fragmentation may result in possibly three to four orders of magnitude more discrete particles by the end of the simulation. Earlier work on discrete element techniques was based on the assumption that each element was rigid, but later extension to include local deformation has permitted a more rigorous treatment of both the contact conditions and fracture requirements.
