Preliminary laboratory results of irregularly shaped specimens modeled after irregularly shaped stone pillars

Underground stone or hard rock mines typically employ the room-and-pillar mining method. Room-and-pillar mines are designed in traditional patterns with square or rectangular shaped pillars. This method is favorable because the symmetric pattern aids in optimizing mining operations. In active mines, deviations from the mine plan often result in irregularly shaped pillars. In older mines, which were designed when pillar design methodology was less developed, irregularly shaped pillars are more common than in current operations. The performance of hard rock pillars is primarily based on the pillar's stability factor and the width to height ratio, where the width is the smallest dimension of the rectangular base. The estimation of pillar strength in room-and-pillar stone mines has been studied by researchers and empirical relationships between traditional geometry (square and rectangular), and strength have been developed. Determining the strength of irregularly shaped pillars is integral to determining the pillar and regional stability. This paper presents preliminary laboratory results for specimens with irregular geometry that correspond to odd-shaped pillars and contrast to the strength of traditional specimens. Although a statistically significant difference between the UCS values measured for different specimen geometries was not established, preliminary results indicate that the intact core areas are of different dimensions.