Failure Mechanisms and Pre-Reinforcement Design for Ore Passes under High in-situ Stresses: A Case Study from the Asheler Deep Mine

Abstract

The current deep shaft environment at Asheler features highly stressed expansive rock with well-developed joints, poor surrounding rock stability, and a distinct foliated structure that softens and mudifies upon contact with water. Under joint impacts of high shaft stress and ore impact, existing ore pass has experienced multiple instances of shaft deformation and collapse. Taking the existing deep ore pass at Asheler as the engineering context, ththis study investigates the deformation and failure mechanisms of the surrounding rock during downward excavation (raise boring). Based on these mechanisms, a composite pre-reinforcement system consisting of pre-grouting and a steel-concrete lining is proposed. A numerical model of the pre-grouting diffusion range was constructed using COMSOL Multiphysics. The coupled reinforcement analysis incorporating the grouted zone was subsequently performed using FLAC3D. The numerical results indicate that the proposed pre-reinforcement scheme can effectively control the deformation of the surrounding rock and limit the expansion of the plastic zone, thereby significantly enhancing the safety and stability of the ore pass.