# 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 \(0^{\circ}\), \(45^{\circ}\), and \(90^{\circ}\) 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 \(45^{\circ}\) 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 \(90^{\circ}\) fracture samples exhibiting diminished strength post freezing, while the \(45^{\circ}\) 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. refeze-thaw cycles; fractured rock; rock bolt +
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90\({}^{\circ}\). [PERSON] et al. [8] executed uniaxial compression tests on granitic specimens featuring pre-existing flaw pairs characterized by diverse inclination angles, bridging angles, and ligament lengths, aiming to investigate the development of fractures and the aggregation behaviour of granites. Moreover, the researchers conducted theoretical analyses to elucidate the damage patterns within the rock. [PERSON] et al. [9] conducted numerical simulations on rocks containing trapezoidal joints, revealing that the damage pattern in such jointed rocks was predominantly influenced by joint overlap. [PERSON] et al. [10] utilised the finite element method to analyse the damage process in rocks harbouring prefabricated fractures, facilitating the prediction of the emergence and propagation of new cracks in prefabricated fractured rocks. [PERSON] et al. [11] established a \"rock-coal-bolt\" (RCB) composite system and scrutinised the action mechanism of anchors under tensile and shear stresses. Meanwhile, [PERSON] et al. [12] developed a damage model for fractured rocks subjected to cyclic loading from the perspective of energy dissipation and analysed the evolution patterns of the elastic modulus and residual strain in fractured rocks. In the domain of freeze-thaw cycling, extensive experimental and numerical investigations have been conducted to probe the ramifications of such cycles on the toughness, fracture mechanisms, and fatigue deterioration of rocks. [PERSON] et al. [3] investigated the impact of temperature fluctuations, exposing specimens to 0, 5, 10, 20, and 30 freeze-thaw cycles, and noted a non-linear decline in both the type I and type II fracture toughness of sandstones with the increasing cycle count. [PERSON] et al. [13] conducted a detailed examination of the mechanical properties of sandstone subjected to 20 to 40 and 40 to 60 freeze-thaw cycles, observing changes in damage morphology and a reduction in both Brazilian tensile strength and uniaxial compressive strength. As the number of freeze-thaw cycles increased, the primary failure mode of the sandstone transitioned from axial splitting to shearing along a single plane in the UCS tests, and from central smooth fractures to central zigzag fractures in the BTS tests. [PERSON] et al. [14] observed that freeze-thaw cycles induce notable localized fatigue damage around the crack tips in sandstone specimens.