Steeply dipping, vein and tabular orebodies are traditionally extracted with longitudinal retreat mining methods such as Eureka and Avoca in a bottom-up sequence with delayed backfill. To increase productivity, sill pillars in the orebody are used to separate mining zones thus allowing production to take place simultaneously in two or more zones. While such mining methods are productive, they may be accompanied with high volumes of hanging wall overbreak causing significant unplanned ore dilution. In this work, it is shown through a mine design case study of a narrow vein deposit that a sill pillar could also play a significant role in limiting hanging wall overbreak. To demonstrate the role of sill pillar, a novel numerical modelling scheme is proposed to account for progressive stope wall overbreak. A numerical modelling approach of element death and rebirth is developed to allow for the detected stope overbreak to be immediately removed and replaced with backfill material before upper-level stope extraction. It is further shown that the average overbreak volume could be reduced by as much as 33% when the sill pillar is strategically placed in the lower half of a mine plan.

陡倾、脉状和板状矿体传统上采用纵向后退采矿方法（如 Eureka 和 Avoca）以自下而上的顺序提取，延迟回填。为了提高生产力，矿体中的门槛柱用于分隔采矿区，从而允许在两个或更多区域同时进行生产。虽然这种采矿方法是有生产力的，但它们可能伴随着大量的悬壁超挖，导致大量的计划外矿石稀释。在这项工作中，通过对狭窄矿脉矿床的矿山设计案例研究表明，门槛柱也可以在限制挂壁超挖方面发挥重要作用。为了证明门槛柱的作用，提出了一种新的数值建模方案来解释采场壁的渐进式超挖。开发了单元死亡和重生的数值建模方法，以允许在上层采场提取之前立即移除检测到的采场超裂并用回填材料替换。进一步表明，当门槛柱被战略性地放置在矿山计划的下半部分时，平均超挖量可以减少多达 33%。