Abstract
ABSTRACT: A quantitative assessment of Fall of Ground (FoG) hazards is essential for effective geotechnical risk management in underground excavations. Despite advances in ground control technology, FoG remains a persistent threat to underground mining operations. In this study, a dimensionless FoG Index is introduced to quantify FoG hazard based on documented FoG occurrences. The methodology employs the Analytic Hierarchy Process (AHP), a multi-criteria decision analysis technique used here to systematically determine the weights of FoG-related parameters and to reduce subjectivity in the evaluation process. Welldocumented FoG cases from East Sary-Oba mine, an underground mine in located in central Kazakhstan were used to establish and calibrate the FoG Index. The dataset included FoG size, excavation types, excavation support, excavation geometry, and rock mass characteristics. The proposed index was compared with the observed FoG, yielding a strong correlation (R = 0.77). In addition, the analysis identified support design and geological structures of the surrounding rock mass among the most influential factors controlling FoG occurrence. Overall, the results indicate that the FoG Index can serve as a practical tool for guiding ground control strategies and improving geotechnical risk management in underground mines.