Cratering Prediction due to Block Caving

A numerical approach to cave assessment has been developed by Itasca over the past 15 years through the industry-funded International Caving Study (ICS I & II) and Mass Mining Technology (MMT) projects. The procedure has been implemented successfully in the calibration and simulation of cave responses at a number of existing and planned caving projects. In this paper, the procedure is used to simulate block caving for an ongoing underground mining operation, which has been active for more than 40 years. Due to limitations in accessing available information, the problem was posed to reproduce caving and cratering for the last 10 years, starting with the presence of a known cave representing mining in previous years. The algorithm to simulate caving has been implemented within the three-dimensional, continuum based program, FLAC3D, following a rigorous mass-balance routine to ensure that the design production schedule is represented accurately. A constitutive model specially designed to represent caving behavior has been recently developed by Itasca applying the concept of strain-softening (CaveHoek constitutive model), whereby strain-dependent properties are adjusted to represent the effects of dilation and bulking that accompany caving. The main outcome of the study is to compare the simulated cratering at the surface against the known topography at the end of the simulation period. The validation of the field observations provides increased confidence about the model predictions for future mining operations.