Effect of the Rock Stress on the Water Jet Cutting Performance

Underground quarrying is rarely adopted for granite extraction due to the difficulties in the implementation of traditionaltechnologies (drilling and explosive). As alternative to drilling and explosive, the combination of diamond wire and waterjet seems to be the most promising available technology. The cutting performance achievable with the water jet technologydepends on the operative parameters, the material characteristics and the state of stress within the rock massif. To assess theeffect of the state of stress on the cutting rate, laboratory tests have been performed with an oscillating water jet machine ongranite samples subjected to a static load. The stress distribution in the layer of rock to be removed has been evaluated bynumerical simulation with the FLAC code (Fast Lagrangian Analysis of Continua). The correlation between the results ofthe cutting tests and the numerical models of the rock samples has been inferred. Starting from a conceptual model, whichtheoretically describes the relationship between the cutting rate and the stress, a step function was defined that indicates theranges of stress where predefined values of the cutting rate are workable.