Investigation of Yielded Zone in Block Caving Method using Finite Element Modeling and Plastic Strain Rate Criteria

In the last decade, the block caving method has been being proposed to use as the best option for large-scale and low grade deposits in depths. This method is one of the most important methods which can compete from productivity point of view with surface mining methods. However, the accurate understanding of geotechnical problems in caving have been asserted by plenty of operational experience in large block caving mines. In addition, the ability of caving (cavability of ore and cap rock) is the most important factor to apply this technique. Also underestimate of this variable not only can cause many problems in processing but also in the worst case tend to fail the project. Analysis of regions duo undercutting to ensure the accuracy of predicted caving is very useful in various mines. Mechanical and geometry properties of joints by using jointed material inserted in the model. The results proved that not only by increasing strength parameters of the rock mass height of Yield zone was decreased, but also by increasing dip angle of the joint the height of Yield zone was reduced. In addition, the results showed that the more dip angle of joint height we have, the less yield zone we have. Also the Joint friction angle has the most effective on height of Yield zone. In fact rock mass with dip of joints 20 degrees has the highest height of Yielding zone. This reduction had occurred in the range of 30 to 45 degrees by low gradient and in the range of 45 to 80 by a high gradient.