Key Takeaways & Executive Findings
- •• Maximum shear load decreases by 36.81% to 46.94% as dynamic normal load amplitude increases from 10% to 70%, with rock type influencing the extent. • Rock type critically controls the localization of shear failure surface, leading to differentiated wear characteristics and failure modes. • DEM simulations reveal nonuniform contact force chains and rock-type-dependent crack propagation pathways under dynamic normal load boundaries. • Anisotropic interface damage factor increases from 34.9% to 56.6% with increasing amplitude, but decreases from 49.6% to 23.4% when rock type changes from coal to limestone.
Abstract
Under external disturbances, the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring system composed of multiphase media are inherently difficult to characterize due to the concealment nature of interfacial interactions. This study establishes an equivalent shear model for a bolt-resin-rock anchoring system and conducts direct shear tests under dynamic normal load (DNL) boundary from both laboratory experiments and discrete element method (DEM) simulations. The research investigates the influence of normal dynamic load amplitude (An) and rock type on shear strength parameters, elucidating the evolutionary characteristics and underlying mechanisms of shear load and normal displacement fluctuations induced by cyclic normal loading, with maximum shear load decreasing by 36.81% to 46.94% as An increases from 10% to 70% when rock type varies from coal to limestone. Through analysis of strain field evolution, the critical impact of rock type on localization of shear failure surface is revealed, with systematic summarization of differentiated wear characteristics, failure modes, and key controlling factors associated with shear failure surface. Mesoscopic investigations enabled by DEM simulations uncover the nonuniform distribution of contact force chains within the material matrix and across the anisotropic interfaces under various DNL boundaries, clarify rock type dependent crack propagation pathways, and quantitatively assess the damage extent of shear failure surface, with the anisotropic interface damage factor increasing from 34.9% to 56.6% as An rises from 10% to 70%, and decreasing from 49.6% to 23.4% as rock type varies from coal to limestone.
1. Introduction
In the field of underground engineering, anchoring systems serve as a crucial active support form to ensure the stability of engineering structures. However, the long-term stability of anchoring systems during service is confronted with multiple challenges, including the complexity of geological conditions, the heterogeneity of surrounding rocks, and the dynamic disturbances induced by mining activities, earthquakes, and roof collapses [1,2].
Anchoring systems are mainly composed of anchor bolts, anchoring agents (adhesives), and surrounding rocks, as shown in Fig. 1. Among these components, in addition to the mechanical performances of materials themselves, the chemical or physical adhesion and structural interlocking forces between different materials, particularly at anisotropic interfaces, are key factors in maintaining the stability of anchoring systems [3]. Studies by Cui et al. [4] and Zhang et al. [5] demonstrate that dynamic loads such as earthquakes or blasting can alter the normal stress on faults and rock joints, indicating that the dynamic disturbances not only exist in shear direction but also require attention to normal components. Under dynamic normal load (DNL) boundaries, the shear mechanical responses and debonding failure mechanisms at anisotropic interfaces of anchoring systems remain critical scientific issues that urgently demand in-depth exploration.
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Xinxin Nie, Qian Yin, Zhigang Tao, Manchao He, Gang Wang, Wenhua Zha, Zhaobo Li, Yajun Ren (2025). Shear mechanical responses and debonding failure mechanisms of bolt-resin-rock anchoring system under dynamic normal load boundary. SinoTechIntel Verified Research. https://doi.org/10.1016/j.ijmst.2025.08.005
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Frequently Asked Questions
What is the effect of dynamic normal load amplitude on the shear strength of bolt-resin-rock anchoring systems?
The maximum shear load decreases by 36.81% to 46.94% as the dynamic normal load amplitude increases from 10% to 70%, with the exact reduction depending on the rock type.
How does rock type influence the failure mechanisms in anchoring systems under dynamic normal load?
Rock type critically controls the localization of the shear failure surface, leading to differentiated wear characteristics, failure modes, and crack propagation pathways, as revealed by strain field analysis and DEM simulations.
What is the role of DEM simulations in studying anchoring systems under dynamic normal load?
DEM simulations provide mesoscopic insights into the nonuniform distribution of contact force chains, rock-type-dependent crack propagation, and quantitative assessment of damage extent, such as the anisotropic interface damage factor.
What are the key findings regarding the anisotropic interface damage factor?
The anisotropic interface damage factor increases from 34.9% to 56.6% as the dynamic normal load amplitude rises from 10% to 70%, but decreases from 49.6% to 23.4% when rock type changes from coal to limestone.
Why is it important to study anchoring systems under dynamic normal load boundaries?
Dynamic disturbances such as earthquakes and blasting can alter normal stress on faults and rock joints, affecting the stability of anchoring systems. Understanding shear mechanical responses and debonding failure mechanisms under such conditions is crucial for ensuring long-term stability in underground engineering.
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