Insight into undercut-induced ground deformations in cave mines

ABSTRACT As underground cave mines transition to greater depths, they face the unavoidable challenge of managing stress-driven instabilities on the extraction level, particularly those resulting from high abutment stresses induced during the undercutting process. The primary objective of undercutting is to establish an adequate stope to initiate caving. However, in deep and high-stress caves, undercutting must also aim to mitigate the impact of high abutment stress effects resulting from the undercutting process. This paper primarily aims to review previous studies on undercut-induced deformation analysis. Secondly, it seeks to understand ground responses to understand the ground responses to undercutting using common displacement monitoring measurements including Multi-Point Borehole Extensometer (MPBX) and convergence pins. Three cave mines objectively selected to compare ground deformation trends and patterns during undercutting stage. Findings illustrate that the same deformation pattern observed during undercut passes over monitoring locations in all three cases and its rate and magnitude increase as undercut expands. Higher deformations during undercut stage tended to show resumption after undercutting. This highlights the importance of predicting and mitigating stress-induced deformations during undercutting in cave mines.