Abstract:To identify and evaluate the stability of the goaf in the Majiadidi tungsten mine, this study conducted a systematic analysis targeting two types of backfilled goafs in the mining area. The analysis integrated field investigations, three-dimensional numerical simulation, and in-situ monitoring techniques. A refined numerical model of the goaf was established using the coupled 3DMine and FLAC3D method. Initial in-situ stress was determined using the hydrostatic pressure formula to simulate stress, displacement, and plastic deformation characteristics of the roof and floor. Nine monitoring points were deployed in critical roof areas for validation. Results indicate overall stability and safety of the goaf. Field monitoring recorded maximum roof displacement of 24. 11 mm and peak stress of 11. 42 MPa, while numerical simulation projected maximum roof displacement of 25 mm. Both trends align and remain within rock mass safety limits. Stress distribution in the pillar exhibited a “ high in the middle, low at both ends” pattern, with only minor localized shear and tensile failures observed. No continuous plastic failure zones were detected, indicating that the backfilling and sealing measures effectively mitigated risks. These findings provide theoretical support and reference guidelines for evaluating the stability and managing the safety of goaf areas.
