Stoping Sequence Optimization based on Stope Stability Assessment Using Finite Element Modelling Method
Sublevel stoping mining method is widely used in Canada to excavate the steeply dipping orebodies. With such mining method, stope is the basic excavation element, and sill pillars are reserved to prevent the transfer of mining-induced stress among different mining levels, and the mined-out stope voids are backfilled. However, recovering sill pillars can trigger catastrophic problems. To safely recover the sill pillars, a feasible recovery scheme is a great challenge with most mining operations
... n underground mining. To reach the objectives of this research thesis, a Canadian diamond mine was analyzed as the case study and a full size three-dimensional finite element model of the mine was developed by using the finite element method (FEM) with the application of ABAQUS codes. Laboratory tests were conducted to achieve the rock mechanics parameters of kimberlite, backfilled cemented rockfill (CRF). The developed numerical model was calibrated and verified by comparing the data from the FE model and the recorded in-situ date to conduct to proposed analysis. According to the analysis results, firstly, the influences of different excavation and backfilling length effects on the stope sidewalls are almost the same, which makes the numerical modelling analysis productive by combining the excavation and backfilling schedules in large size numerical model. Then, for the optimum location of last mined stope, with the influence of backfilling, last mined stopes during production should be at the center of the level, and in sill pillar recovery, last mined stopes should be at least four-stope-width away from the two mining level edges. For the stability of the boundary of the kimberlite mining pipe, it has higher possibility of instability during the mining activities, especially for the accesses to the stopes in deeper mining levels. Finally, the three proposed schemes of sill pillar recovery were assessed. All three recovery schemes were iii proved to be feasible to recover the sill pillars, and the scheme of starting from both sills (SBS) was the optimum scenario.