Mitigating the effect of specimen size on uniaxial compressive rock strength using a generalised correction and experimental testing method

Abstract

Uniaxial compressive strength is one of the key characteristics of rocks, typically determined by laboratory-controlled destruction of cylindrical specimens. Previous studies have found that the diameter and length-to-diameter ratio of the specimen affect the obtained strength value. The current understanding of the diameter effect is not convincing, and thus considering the low variability of extracted core sizes, the effect can be neglected. The length-to-diameter ratio effect is more distinct and, hence, it represents the main component of the correction models. Previously established corrections of the ratio effect differed in the reference ratio value corresponding to the assumed unaffected strength value. In our paper we propose a new generalised and fully variable correction method built around a single parameter plateauing equation with an additional parameter controlling the target ratio value. In addition to this correction, we also propose a new experimental testing method for unaffected uniaxial compressive strength determination using a set of rock specimens with variable length-to-diameter ratio.