Exploring the deformation characteristics of a steep overhanging anti-dip slope from material mechanics viewpoints

In this study, we investigated the deformation features of steep overhanging anti-dip slopes based on their scale, the rock layer thickness, and the unsupported length. Centrifuge tests were performed for various configurations of simplified overhanging anti-dip slopes. The steep overhanging anti-dip slopes expressed flexural and block toppling behavior in all of the centrifuge tests in this study. The toppling is a progressive behavior: firstly, the shallow rock layers deform slightly as the deformation starts. Afterward, the deformed rock layers toppled, and the rock layers behind them deformed insignificantly. In terms of the scale effect, increasing the slope scale could raise the toppled and deformed zone of the overhanging anti-dip slope. As the unsupported length of the slope is long, the deformation behavior tends to be flexural toppling. When the rock layer thickness increases, the deformation behavior is similar to block or block-flexure toppling. A normalized bending stiffness (K’) is then proposed in this study to discuss the deformation behaviors from material mechanics viewpoints. We found that the K’ is related to the toppling behavior of the overhanging anti-dip slopes. With a small K’ value, the rock layers in an overhanging anti-dip slope deformed close to a flexural toppling. A much smaller K’ value was also obtained for an actual flexural toppling case. Therefore, the findings indicated that the deformability of an overhanging anti-dip slope could be analyzed from a material mechanics viewpoint, and the deformation characteristics depend highly on its normalized bending stiffness.