Abstract:The orepass-crushing system is a critical large chamber in underground metal mines during construction and production phases. Temporary and permanent support methods are essential to maintaining the stability of the chamber during excavation and service periods. Taking the excavation of a large crushing chamber in a Serbian copper mine as an example, the excavation process and support methods were determined based on geological characteristics and operating conditions. Support parameters, such as rock bolts and prestressed long anchors, were calculated using reinforced arch theories. The results show that a single-side pilot drift with positive step layered excavation ensures stability during the excavation of large chambers in poor rock conditions. For the upper-layer arch, the “pilot drift-extension brushing” three-step excavation reduces the vertical displacement of the roof and horizontal displacement of the sidewalls by 27.9% and 35.7%, respectively, compared to one-time full-section excavation. Under combined temporary support (bolts, mesh, shotcrete, and anchors) and permanent support (reinforced concrete), the stress arch in the roof and tensile stress in the sidewalls of the crushing chamber were significantly reduced. The displacement of surrounding rock and the maximum depth of the plastic zone were also effectively minimized, ensuring safety during both the excavation and service periods of the crushing chamber.
