Construction of reasonable pillar group for undersea mining in metal mine

In order to achieve the safe mining in Sanshandao Gold Mine, five schemes of secure pillar group are designed. Using the method of the renormalization group, the failure mechanism of the pillar group is explored, and the safety factor of the pillar system is also obtained. The displacement characteristics, stress–strain laws, distribution of plastic zone and damage range of different pillar group are analyzed using numerical calculation software FLAC^3D. To determine a reasonable pillar group scheme, the pillar stability and roof deformation are utilized to evaluate the safety of the pillar group. In addition, the theory of fuzzy comprehensive evaluation is adopted to verify the optimal scheme. The pillar group with the lowest roof deformation value is chosen as the optimal plan, which renders a factor of safety of 2.06 for the pillar group. According to this scheme, pillars with the width of 10 m are set along the strike of undersea deposit with the interval of 50 m. Rib pillars of 15 m in width are set at the location of the exploration line of 127, 151 and 167. The analysis can be used to provide guidance for optimal design of pillar structures in undersea mining.