A Numerical Simulation of Bolt Grouting Reinforcement for Reducing the Optimum Dimensions of Jointed Hard Rock Pillars in Faryab Chromite Mine (Iran)

The maintaining needed for underground mining operations is satisfied by installing a support system or leaving an ore pillars. These pillars need to have enough stability to bearing the overburden loading. Designing a pillar with optimum dimensions is the most significant issues in room and pillars underground mining method. The purpose of this paper is to determine the optimum dimensions of rock pillars in Faryab mine and reducing their dimensions using grouting technology based on a numerical simulation. The modeling results, before grouting operation, show that in the area where the pillars height is 12 m, the pillars with a width of 8 m are stable and the pillars with a width of 7 m are unstable and are on the verge of destruction. So a pillar with a width of 7 m is considered in order to stabilization. 2D and 3D numerical modeling results show that using bolt grouting in jointed rocks, improved the strength properties and as a result increase the strength of pillars and make it completely stable. Accordingly, in the rock masses that can be injected, the grouting operation can reduce the pillars width and increase the extraction recovery.