Fall of Ground Characterization at East Sary-Oba Mine, Kazakhstan

Fall of Ground (FoG) incidents remain a major safety and operational challenge in underground mining, particularly in structurally complex ground conditions. This study characterizes FoG occurrences at the East Sary-Oba Mine in central Kazakhstan. To this end, a comprehensive database of FoG incidents and their associated geotechnical factors was compiled, processed, analyzed, and visualized. In addition, a representative FoG case was investigated using two-dimensional numerical modeling in RS2 (Rocscience). The analysis showed that FoG sizes range from approximately 1 t to more than 1200 t. Large-scale failures are predominantly concentrated in excavation roofs and are structurally controlled, occurring near faults, shear zones, highly fractured rock masses, and water-affected zones under low confinement conditions. Progressive bed separation and stepwise roof collapse were identified as the dominant failure mechanisms. The analysis further indicated that the current support system, consisting of Steel–Polymer Anchor Support (SPAS) and shotcrete, provides limited effectiveness in structurally disturbed zones. The study concludes that a multi-level reinforcement strategy incorporating deep cable anchors and enhanced shotcrete systems is required to improve excavation stability. The findings provide a basis for excavation-specific support optimization and the development of updated support design guidelines for structurally complex underground mines.