Combined Protection Technology in Deep High In Situ Stress Environment of Metal Mines

Abstract

Deep mining operations in metal mines face escalating challenges from high in situ stress environments, where conventional single-method ground control approaches often prove insufficient. This study proposes an innovative combined protection technology integrating four synergistic components: (i) prestressed rock bolt and plate support for immediate roadway reinforcement, (ii) hydraulic fracturing-based shielding to create fracture zones isolating the orebody from surrounding high-stress regimes, (iii) destress blasting at the orebody crown to form a stress-transfer barrier, and (iv) subsequent cemented paste backfill to provide long-term regional stability. Theoretical formulations are derived for each component: a bolt–rock composite bearing model quantifies the confinement provided by prestressed support; a fracture mechanics-based model characterizes the stress-shielding efficiency of hydraulic fracture networks; controlled blasting theory predicts the stress redistribution achieved through crown destressing; and a backfill arching model evaluates the long-term load-bearing capacity of cemented paste fill. A three-dimensional FLAC3D numerical model was established to simulate six working conditions: no protection, support-only, shield-only, pressure relief-only, backfilling-only, and the integrated four-component system combining support, shield, pressure relief and backfilling. The numerical results reveal that the integrated composite protection system reduces roadway subsidence by 86%. Furthermore, the synergistic effect among all components exceeds the sum of individual contributions, which verifies the necessity of adopting the comprehensive protection strategy under deep high in situ stress conditions. The research findings provide theoretical basis and engineering design references for safe and efficient mining in deep metal mines.