Design optimization of room and pillar mines: a case study of the Xianglushan tungsten mine

This paper presents the design optimization for the Xianglushan tungsten mine using the room and pillar mining technique. The influence of pillar height, pillar length, pillar width, room length and room width on the stability of room and pillars was examined through analyses using the orthogonal experimental design method. The pillar and room sizes were identified as the most critical factors. The types of rock masses in the Xianglushan tungsten mine were identified in terms of rock mass classification and the mechanical parameters of those rock masses were assessed. A numerical model was developed in the continuum-based finite-element program 3D-sigma to simulate the excavation process. Given fixed mining and pillar heights, the maximum room width and minimum pillar width were calculated. A separate calculation was also conducted to assess the stable excavation span using the stability graph method. The results obtained from numerical parametric study and empirical-based analysis are consistent. A comprehensive field monitoring programme is introduced, including the data from acoustic emissions, stresses and displacements. The measured responses of pillars and roof rock demonstrate that the proposed design optimization is effective.