The Bolt Anchorage Performance of Fractured Rock under a Freeze–Thaw Cycle Load

Abstract

In circumstances influenced by freeze–thaw cycles, the strength of rock diminishes, necessitating an in-depth investigation into its corresponding anchoring support schemes. This study conducted experiments on rocks with and without fractures at angles of 0°, 45°, and 90° subjected to freeze–thaw cycles of 0, 10, 20, and 30 iterations. It explored the effects of fracture inclination, anchoring conditions, and freeze–thaw cycles on the mechanical properties of rock. The primary findings from the experiments are as follows: (1) fracture inclination significantly impacts rock strength, with the most pronounced deterioration observed in samples with a 45° fracture, exhibiting strengths and elastic moduli at 28.4% and 73.4%, respectively, of those of fracture-free samples; (2) anchoring effectively controls deformation but concurrently induces stress concentrations, resulting in Y-shaped crack formation around the anchoring rod; (3) the degree of strength reduction due to freeze–thaw cycles is angle-dependent, with fracture-free and 90° fracture samples exhibiting diminished strength post freezing, while the 45° fracture samples’ strength remains largely unchanged. Additionally, this study employed a numerical model, coupling a discrete element method (DEM) with a finite difference method (FDM), to simulate experimental conditions, yielding conclusions consistent with experimental outcomes, and notably revealing a prevalence of tensile cracks over shear cracks within samples under uniaxial compression.

Keywords

• freeze–thaw cycles
• fractured rock
• rock bolt