Design of unconventional underground mine pillars

Faculty Development Competitive Research Grants 2020-2022

Pillars are commonly used in underground mining. They are the main ground support structures in room-and-pillar mining method. Traditionally, room-and-pillar mining is used where the ore deposits are horizontal. In that case, the pillars are always vertical and the loading along the pillar vertical axis. These types of pillars are the conventional pillars, and the pillar height to width ratios range from 0.5 to about 2. When orebodies are thicker, pillars can be taller with height to width rations greater than 2. For pillars with height to width ratios greater than 2, failure may occur in tension due to bending or buckling and conventional pillar design approaches cannot be used. Also, some orebodies are not horizontal but inclined with dips up to 45º. In dipping orebodies, the pillars are inclined. For inclined pillars the total load carried by the pillar is not along the pillar vertical axis.In this research tall and inclined pillars are termed unconventional pillars. there is no defined design approach for unconventional underground mine pillars, and the use of design approaches for conventional pillars is inappropriate for unconventional pillars since the failure mechanisms are different. In this research we plan to identify rock properties and test procedures necessary for the design of unconventional underground mine pillars.