Rock engineering and its obsession with rock bridges: why everything we call real cannot be regarded as real

Abstract

Rock bridges are critical in determining the stability of rock slopes and underground excavations. However, measuring them is impossible since their definition extends beyond a mere geometrical problem. Rock bridges are understood primarily in the context of rock mass strength, representing known unknowns akin to the principle of complementarity in physics. The current understanding suggests that while we can measure rock bridges post-failure, their pre-failure definition and measurement elude us. Historically, researchers have focused on the geometric perspective of rock bridges, with limited attempts to investigate actual field evidence. This has led to a disconnect between the theoretical problem and practical measurement. Since Terzaghi first highlighted this issue in 1962, more progress has yet to be made in addressing the fundamental limitations of our understanding of rock bridges. This paper argues for a paradigm shift towards analyzing rock bridges through the lens of rock mass damage and recognizing that rock bridge strength is directionally dependent.