The Effect of Overburden and Confined Stress State on Cave Mining Propagation
DOI:
https://doi.org/10.17159/Abstract
This paper describes a physical modelling approach adopted in an investigation to simulate the process of cave mining propagation at various horizontal to vertical stress state ratios whereby image data was captured and used to observe resulting failure mechanisms. Image processing was integrated into the study to determine minor principal strains in models to identify where critical extensional strains had been exceeded relative to crack propagation. The study exhibited that a scale factor magnitude of 119 was achieved using a calculated critical extensional strain value of 0.014 % for the modelling material used. It was perceived that cave propagation occurred through successive parallel extensional ‘fracture bands’ in all cases as noticed in models of prior studies (namely that of Cumming-Potvin, 2016a) and dissimilar to that which is described by the Duplancic model. Cracks tended to bisect regions of minor principal strain equal to the critical extensional strain which suggests ‘fracture banding’ is an acceptable failure mode for brittle, rock-like materials. Moreover, it was found that models with lower horizontal to vertical stress ratios (K ratios) showed a greater degree of vertical development of the caving mechanism (at similar vertical stresses), whilst the vertical extent of the cave was suppressed in models with higher K ratios. Models subjected to larger vertical stresses experienced slower cave formation in latter time-steps. These models resulted in exhibiting larger two-dimensional caved perimeters and areas, respectively.Downloads
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Copyright (c) 2024 Nicholas Kyle Schoeman, Schalk Willem Jacobsz, Elsabe Kearsley, Johan Wesseloo
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