GRANULAR FLOW MODELS AND DILATION FRONT PROPAGATION APPLIED TO UNDERGROUND MINING

Underground mining has become a viable alternative method for ore extraction when the operation cost of an open pit mine becomes too high. Its success is based on a good characterization of the rocks flow inside the cave. Kinematic and plasticity models, used in the granular flow description in hoppers, have been adapted to describe the experimental situations aimed at sketching the mine operation. The local packing changes that occur at the early stages of rock motion that significantly affect the flow are considered by introducing a dilation front propagating upward. The dynamics of the dilation front limits the extent of the flow generated by the drawing process allowing the assessment of the loosening zone. Based on the linear character of the kinematic model, it is shown that the loosening zone resulting from the simultaneous extraction at two adjacent draw points is accurately described by the dilation front approach.