Mechanical stability of intensifying mining for residual ore under complicated goaf groups

摘要

Three commonly used rock mass classification systems, i.e. RMR, BQ and Q systems, are used for evaluation of rock mass quality in Xianglushan tungsten mine. Generalized Hoek-Brown criterion is partially modified by introduction of disturbance factor D to treat mechanical parameters for various rock mass. Then, parameters for calculation of pillar strength are determined according to the derived formula of the pillar load. On this basis, the sensitivity of influential factors for pillar stability is assessed using the method of orthogonal range analysis. At last, orthogonal design is introduced into the optimization of stope span and pillar dimensions by 3D-σr FEM simulation. Meanwhile, stope exposure area at rock failure can be estimated based on Mathews stability graph. Research achievements have been widely adopted by Xianglushan tungsten mine in China. Additionally, various methods of ground pressure monitoring are applied to ensure the stability of the retention pillar, and the safety of goaf around the tope. Field application shows that pressure monitoring results are reliable, stope structural parameters meet the mine production of objective reality.