Mechanical Response and Failure Mechanism of Rock with Holes Under Multiple Stress Gradients
摘要
In underground rock engineering, the stress state of the surrounding rock undergoes repeated adjustments throughout the service period, resulting in a highly heterogeneous distribution of stress gradients. This complex stress environment is a key factor contributing to rock failures. To investigate stress migration patterns and the mechanisms of failure in rock with holes under varying stress gradients, this study proposes a novel experimental method. It addresses the limitations of existing rock mechanics tests by enabling the internal simulation of continuous multiple stress gradients (MSG) fields in rock specimens. Microscopic crack propagation and macroscopic strain evolution in rock with holes are analyzed using acoustic emission (AE) and digital image correlation (DIC) monitoring technologies. Numerical simulations, combined with theoretical analysis, are used to study stress distribution and migration patterns. A multi-method and multi-angle analysis identifies the instability mechanisms of rock with holes under multiple stress gradients. The results show that variations in stress gradient differences play a critical role in governing crack patterns. As the differences in stress gradients increase, the proportion of tensile cracks in rock with holes rises significantly. The shear stress concentration zone around the holes tends to migrate toward regions with greater gradient variations, while tensile action becomes more pronounced in areas with smaller gradient changes. Integrating strain evolution and failure mode analysis reveals that changes in multiple stress gradients lead to significant alterations in the failure behavior of rock with holes. These conclusions provide deeper insights into the mechanical behavior of rock with holes under multiple stress gradients and offer practical guidance for developing protective measures in underground rock engineering subjected to such stress conditions.