Numerical and Experimental Study on a Novel Filling Support Method for Mining of Closely Spaced Multilayer Orebody

Mining of closely spaced multilayer orebodies brings the problems of significant disturbance between adjacent mining layers and drastic structural changes in surrounding rock, which brings the need for a more effective stope support method. Previous research has made sound analysis on filling or bolt support, but neither of them can solely provide ideal support effects. Thus, a novel bolt-filling support method is proposed by utilizing the synergistic effect of rock bolts (cable bolts) and filling. Numerical simulation and similarity experiments were conducted in this research to analyze the support effect of this method for multilayer ore mining. For numerical simulation, the distinct-element modelling framework PFC2D (Particle Flow Code in 2 Dimensions) was applied for four support scenarios based on the calibration of the microscopic parameters of particles in vanadium shale ores. The numerical simulation results show that the number of fractures decreases from 1311 without support through 652 with 95% filling support to 410 with bolt-filling support, which is resulted from the redistribution of the force chains due to support change. On the other hand, a 300 cm x180 cm x 40 cm similarity model with a geometry similarity constant of 100 was established based on the 4# rock layer profile of Mount Shangheng. Two parts of similarity experiments were conducted to investigate the strains around the stopes in multi-layer ore mining for three support scenarios. The experiment results prove that the highest strain is in the center of the roof on the upper goaf, and the roof-bolt filling support induces smaller strains than zero support and conventional filling support. Finally, an effective bolt-filling support system has been developed and validated, which can improve the safety and the stability of the roofs and interlayers during the mining process of closely spaced multilayer orebody by reducing the overall load and fractures in surrounding rock.