Mechanism Underlying Rock Core Disking Phenomenon—A Theoretical Investigation

In this paper, the rapid axial unloading induced spontaneously rock core disking (or the interval fracture of rock pillar) is regarded as a self-sustained fracture. Mechanical model of rock pillar with initial stress subjected to rapid axial unloading under constant radial stress is established, the process of rock core disking is theoretically reproduced, and mechanism underlying the fracture process is analyzed. The expression that could not only reflect the relationship between the dimensionless core thickness d/D and the dimensionless initial axial stress \({{{{\sigma }_{1}}} \mathord{\left/ {\vphantom {{{{\sigma }_{1}}} {{{\sigma }_{t}}}}} \right. \kern-0em} {{{\sigma }_{t}}}}\), but also could reflect the influence factors on critical stress of rock core disking is deduced. Among the influence factors, the residual energy ratio is the most important one, the critical stress reaches its minimum value if \({{K}_{{\rm I}}} = {{K}_{{{\rm I}C}}}\). By referring the field test data from URL of Canada in the existing study, the expressions for granite and granodiorite with parameters determined are presented, the residual energy ratio and critical stress of rock core disking are also calculated.