Mechanical behavior and tensile bearing performance of anchorage body under the influence of structural plane dip angle

Abstract

With increasing mining depth in metal mines, the stability of roadway support structures is significantly affected by the complex surrounding rock. This study performs biaxial compression and bolt pull-out experiments on anchorage body specimens with different structural plane dip angles to explore failure mechanisms of anchorage structures and evolutionary law of bolt anchorage force. Results show the dip angle notably impacts the bearing capacity and failure modes of anchorage specimens. Their peak stress exhibits a V-shaped trend: decreasing from 54.80 MPa to 19.65 MPa as dip angles increase from 0° to 45°, with failure mode transitioning from tensile to shear; at 60°, it becomes a tensile-dominated mixed mode. Bolt anchoring significantly enhances bearing capacity (most remarkably by 153.22% at 45°) and changes failure from brittle to ductile. Pull-out tests reveal two failure modes: slip at the bolt-rock interface and bolt fracture. At 45°, bolt fracture occurs under a 14.55 kN peak pull-out load, matching the bolt’s yield strength. This failure mechanism involves two key factors: structural plane sliding that shears the bolt, and mechanical interlocking that restricts pull-out, substantially increasing anchorage force. These findings provide insights for stability assessment and support design of roadway structures in complex geological environments.

Keywords

metal mine / roadway support / structural plane / split-set bolt / anchorage force

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Central South University