Abstract
Mining and tunneling in weak and highly fractured rock, soft soils and mixed ground present challenges in maintaining a safe working environment, excavation stability and operational efficiency. Traditional ground support systems - such as reinforcement (grouted rebar, friction bolts and cable bolts) and surface support (mesh, shotcrete and shotcrete ribs /arches) - commonly used in mining industry often prove ineffective for very poor ground conditions.
This paper introduces an innovative ground support system which combines use of self drilling anchor and shotcrete to address these challenges. The support system provides both active and passive support functions. Self drilling anchor serves as rock reinforcement, consolidating rock mass and enhancing rock mass strength. Additionally, they can be used for spiling as pre-support, as well as for stabilizing faces for large-section excavations. Shotcrete, when applied in weak ground, has two functions: (a) to act as a structural arch support the ground pressure, and (b) to seal the exposed ground immediately after excavation to prevent loose material form unraveling, reactive rock / soil materials from swelling, face instability and ground collapse.
This paper outlines essential design considerations, practical approaches for pre-reinforcement and support in weak rock, and implementation measures. Three case studies illustrate the application of these pre-reinforcing and support measures in underground mining and tunneling, demonstrating improved excavation stability and reduced cycle time to enhance productivity.