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<p>The focus is on a high prestress, high elongation NPR (Negative Poisson Ratio) anchor cable. Based on the static tensile curves of NPR and conventional PR (Poisson Ratio) anchor cables, constitutive relationships for both types of anchor cables under prestress were established. Using this, a unified strength theory, which reflects the effect of intermediate principal stress, was selected to analyse a deeply buried circular roadway. Equations for the interaction between NPR support and surrounding rock, as well as PR support and surrounding rock (NUST/PUST), were established. Taking a typical kilometre-deep roadway as an example, the solutions were discussed and applied. The results show that the mechanical state proportion of the anchor cables in the roadway section is a quadratic function of the lateral pressure coefficient <i>λ</i>. When <i>λ</i> ≥ 0.7, all NPR anchor cables enter a constant resistance stage, while PR anchor cables break. For different <i>λ</i> values, the characteristic curve of NPR support intersects with the characteristic curve of the surrounding rock, and the elongation reserve is high. This allows the entire roadway's surrounding rock to remain stable. However, for PR anchor cables, after <i>λ</i> ≥ 1, the characteristic curves of the surrounding rock and PR support no longer intersect or barely intersect, resulting in instability or quasi-stability of the surrounding rock. Based on the NUST equation, an NPR coupling support design method was developed. The method was applied onsite at the Wanfu Mine at -950&#xa0;m level (buried depth of 1040&#xa0;m). The results show that after using NPR support, the surrounding rock at the -950&#xa0;m level eventually stabilized, avoiding large deformation and failure phenomena seen at the -820&#xa0;m level with PR support. The results of this study provide theoretical guidance and technical support for safe deep resource extraction.</p>

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Theoretical Analysis and Engineering Application of the Interaction Between NPR Anchor Cable and Deep Surrounding Rock Considering Intermediate Principal Stress

  • 期刊论文

  • 发表日期：

    2025年7月11日

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  • Li Cui,
  • Xiaoming Sun,
  • Ran Hai,
  • Jianjun Ma,
  • Chaosheng Wang

摘要

The focus is on a high prestress, high elongation NPR (Negative Poisson Ratio) anchor cable. Based on the static tensile curves of NPR and conventional PR (Poisson Ratio) anchor cables, constitutive relationships for both types of anchor cables under prestress were established. Using this, a unified strength theory, which reflects the effect of intermediate principal stress, was selected to analyse a deeply buried circular roadway. Equations for the interaction between NPR support and surrounding rock, as well as PR support and surrounding rock (NUST/PUST), were established. Taking a typical kilometre-deep roadway as an example, the solutions were discussed and applied. The results show that the mechanical state proportion of the anchor cables in the roadway section is a quadratic function of the lateral pressure coefficient λ. When λ ≥ 0.7, all NPR anchor cables enter a constant resistance stage, while PR anchor cables break. For different λ values, the characteristic curve of NPR support intersects with the characteristic curve of the surrounding rock, and the elongation reserve is high. This allows the entire roadway's surrounding rock to remain stable. However, for PR anchor cables, after λ ≥ 1, the characteristic curves of the surrounding rock and PR support no longer intersect or barely intersect, resulting in instability or quasi-stability of the surrounding rock. Based on the NUST equation, an NPR coupling support design method was developed. The method was applied onsite at the Wanfu Mine at -950 m level (buried depth of 1040 m). The results show that after using NPR support, the surrounding rock at the -950 m level eventually stabilized, avoiding large deformation and failure phenomena seen at the -820 m level with PR support. The results of this study provide theoretical guidance and technical support for safe deep resource extraction.