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<p>Rock bolts are widely used to improve the stability of geotechnical structures, yet traditional rock bolts can fail under high in-situ stress and seismic conditions. Negative Poisson’s Ratio (NPR) rock bolts, which exhibit lateral expansion under tensile stress, have been investigated as an alternative for such challenging conditions. This research focuses on the deformation performance and energy evolution of NPR rock bolts under shear loading, considering variations in joint roughness and normal stiffness. Experimental findings indicate that the shear strength of NPR rock bolts rises noticeably with increased joint roughness and normal stiffness. Under high normal stiffness, NPR bolts can fully utilize their deformation potential, thus improving the stability of the supporting system. At the same normal stiffness, traditional rock bolts show a maximum shear displacement of less than 6&#xa0;mm, while NPR bolts undergo ductile deformation without necking, achieving shear displacements over 15&#xa0;mm. Energy absorption analysis reveals different force–displacement response mechanisms between NPR and conventional bolts. Owing to their negative Poisson’s ratio effect, NPR bolts exhibit better flexibility and energy dissipation capacity, with peak absorbed energy reaching up to 225.5% of that of traditional bolts. Acoustic emission monitoring further verifies that NPR bolts release energy stably, featuring a lower event rate and slight amplitude fluctuations, which implies gradual crack propagation and no abrupt micro-crack bursts. In addition, NPR bolts are resistant to necking and brittle fracture, contributing to more uniform stress distribution and reducing localized stress concentrations.</p>

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Shear-Induced Deformation and Energy Evolution of NPR Rock Bolts Under Varying Constant Normal Stiffness

  • 期刊论文

  • 发表日期：

    2025年11月27日

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  • Chun Zhu,
  • Ming Huang,
  • Manchao He,
  • Yujing Jiang,
  • Hanfang Zheng,
  • Yalong Jiang,
  • Zhonghu Wu

摘要

Rock bolts are widely used to improve the stability of geotechnical structures, yet traditional rock bolts can fail under high in-situ stress and seismic conditions. Negative Poisson’s Ratio (NPR) rock bolts, which exhibit lateral expansion under tensile stress, have been investigated as an alternative for such challenging conditions. This research focuses on the deformation performance and energy evolution of NPR rock bolts under shear loading, considering variations in joint roughness and normal stiffness. Experimental findings indicate that the shear strength of NPR rock bolts rises noticeably with increased joint roughness and normal stiffness. Under high normal stiffness, NPR bolts can fully utilize their deformation potential, thus improving the stability of the supporting system. At the same normal stiffness, traditional rock bolts show a maximum shear displacement of less than 6 mm, while NPR bolts undergo ductile deformation without necking, achieving shear displacements over 15 mm. Energy absorption analysis reveals different force–displacement response mechanisms between NPR and conventional bolts. Owing to their negative Poisson’s ratio effect, NPR bolts exhibit better flexibility and energy dissipation capacity, with peak absorbed energy reaching up to 225.5% of that of traditional bolts. Acoustic emission monitoring further verifies that NPR bolts release energy stably, featuring a lower event rate and slight amplitude fluctuations, which implies gradual crack propagation and no abrupt micro-crack bursts. In addition, NPR bolts are resistant to necking and brittle fracture, contributing to more uniform stress distribution and reducing localized stress concentrations.