Abstract
The size effect in rock mechanics has long been a challenging issue, with the length-to-diameter (L/D) ratio emerging as a critical factor that has received substantial attention. Understanding the L/D ratio effect is essential for ensuring the accuracy and reliability of laboratory tests. This paper presents a comprehensive review of studies on the L/D ratio effect in rocks, examining its influence on static and dynamic mechanical behavior. The analysis encompasses the effects of specimen L/D ratio on rock mechanical properties, energy characteristics, and failure modes, integrating the findings from theoretical research and experimental studies. The results reveal that the L/D ratio effect varies significantly under different external loading conditions. Despite extensive research, the mechanisms underlying the L/D ratio effect remain ambiguous, and a unified conclusion has yet to be reached. This review highlights the importance of selecting appropriate specimen dimensions for laboratory tests and emphasizes the need for further investigation into the L/D ratio effect to advance the understanding of rock mechanics.