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<p>This study investigates the failure characteristics and anchorage mechanisms of tunnel face anchorage systems under combined dynamic and static loading conditions. It explores rock mass failure modes, as well as the influence of different anchorage methods on the mechanical properties and energy absorption efficiency of the rock mass. The experiments were conducted using a novel three-dimensional and five-surface dynamic loading system (with a static load capacity of up to 20 MN and dynamic load amplitude up to 1 MN), employing 400 × 400 × 400&#xa0;mm rock-like specimens. These specimens were used to simulate near-peak low-amplitude cyclic disturbance in burst-prone stress regimes, which are representative of deep underground and high-stress conditions. The Particle Flow Code-Granular Bond Model (PFC-GBM) was developed to model the rock-like material, which investigates the mechanisms of reinforcement and crack arrest in anchored rock. A flat joint model was employed using the Discrete Element Method (DEM) to simulate trilinear slip at the interfaces the bolt–grout and grout–rock interfaces. This study compares the performance of no anchorage, conventional rebar bolts, and the new Ductile-Expansion rock bolts. It reveals that under unanchored conditions, rock mass failure is concentrated and violent, presenting a brittle-dominated fracture mode. Under static loading, rebar bolts can partially constrain the expansion of certain rock fractures, but their effectiveness is limited under dynamic disturbances. The Ductile-Expansion rock bolts demonstrate excellent crack suppression under both static and dynamic loading conditions. The distribution of fractures is more uniform, reducing localized stress concentrations and allowing the rock mass to undergo a longer plastic deformation phase during loading. A significant amount of energy is dissipated through plastic deformation rather than being abruptly released through crack propagation. This highlights the energy absorption capacity and enhanced confining pressure stability provided by the Ductile-Expansion rock bolts.</p>

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Anchoring Mechanism of Tunnel Free Face Subjected to Dynamic–Static Combined Load

  • 期刊论文

  • 发表日期：

    2026年2月19日

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  • Yu Chen,
  • Zinuo Deng,
  • Linchong Huang,
  • Hang Lin,
  • Yixian Wang,
  • Yu Liang,
  • Cungang Lin

摘要

This study investigates the failure characteristics and anchorage mechanisms of tunnel face anchorage systems under combined dynamic and static loading conditions. It explores rock mass failure modes, as well as the influence of different anchorage methods on the mechanical properties and energy absorption efficiency of the rock mass. The experiments were conducted using a novel three-dimensional and five-surface dynamic loading system (with a static load capacity of up to 20 MN and dynamic load amplitude up to 1 MN), employing 400 × 400 × 400 mm rock-like specimens. These specimens were used to simulate near-peak low-amplitude cyclic disturbance in burst-prone stress regimes, which are representative of deep underground and high-stress conditions. The Particle Flow Code-Granular Bond Model (PFC-GBM) was developed to model the rock-like material, which investigates the mechanisms of reinforcement and crack arrest in anchored rock. A flat joint model was employed using the Discrete Element Method (DEM) to simulate trilinear slip at the interfaces the bolt–grout and grout–rock interfaces. This study compares the performance of no anchorage, conventional rebar bolts, and the new Ductile-Expansion rock bolts. It reveals that under unanchored conditions, rock mass failure is concentrated and violent, presenting a brittle-dominated fracture mode. Under static loading, rebar bolts can partially constrain the expansion of certain rock fractures, but their effectiveness is limited under dynamic disturbances. The Ductile-Expansion rock bolts demonstrate excellent crack suppression under both static and dynamic loading conditions. The distribution of fractures is more uniform, reducing localized stress concentrations and allowing the rock mass to undergo a longer plastic deformation phase during loading. A significant amount of energy is dissipated through plastic deformation rather than being abruptly released through crack propagation. This highlights the energy absorption capacity and enhanced confining pressure stability provided by the Ductile-Expansion rock bolts.