Robust Design of Pillar Arrangement for Safe Room-and-Pillar Mining Method

The arrangement of pillars is a key design parameter in the execution of the room-and-pillar mining method. The objective of this study is to provide safe, reliable and a robust design for pillar arrangements for economic and efficient mineral recovery. Four design parameters have been considered in this study, including the degree of pillar superposition, pillar stiffness, and the pillar width; and the distance between crown pillars. The numerical analysis shows that the stability of mines is significantly affected by the discordance of the pillar arrangement between adjacent levels along with four design factors (e.g. pillar stiffness, overlap ratio, and width and thickness of the crown pillar). The pillar stiffness had the highest average affecting ratio (e.g. 71.8%), while the average affecting ratios of the pillar width, thickness of the crown pillar, and pillar overlap ratio were 18.9%, 5.77%, and 3.6%, respectively. The stiffness had the greatest influence on the safety factor when the strength/stress ratio was used to calculate the safety factor.