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腐蚀环境下预应力锚杆破坏规律研究

Study on the Failure Patterns of Prestressed Anchor Rods in Corrosive Environments

  • 摘要: 预应力锚杆在地下复杂环境中长期赋存,长期拉应力作用与腐蚀环境浸润均会导致锚杆产生性能劣化,现有研究多集中在单纯环境介质因素下的锚杆腐蚀,而对于应力与腐蚀介质耦合下的力学性能劣化的分析研究较少。选取工程上常用的HRB400螺纹钢锚杆作为研究对象,针对锚杆在腐蚀环境中的耐久性问题进行研究。采用恒变形法探究应力腐蚀环境下锚杆材料的形貌破坏特征,同时利用自主研发的应力腐蚀试验设备,研究了恒定预应力和氯盐腐蚀共同作用下锚杆拉伸性能的退化规律。此外,结合数值分析,进一步探讨了长期氯盐腐蚀环境对边坡支护预应力锚杆及边坡稳定性的影响。研究结果表明:在氯盐腐蚀环境下,锚杆杆体表面会出现微小裂纹和点状坑蚀,存在局部加速腐蚀区域。随着时间推移或应力增加,这些腐蚀坑会变得更加明显。在恒定预应力和氯盐腐蚀的共同作用下,虽然锚杆的抗拉强度略有降低,但仍符合规范要求。然而,值得注意的是,受拉后的锚杆杆体延伸率显著下降,已接近规范的下限值。通过数值模拟分析发现,锚杆力学性能劣化会导致边坡位移量增加、坡顶出现的张拉破坏以及剪切破坏区逐步扩大。随着腐蚀程度不断加剧,可能形成滑移贯通面,从而显著降低了边坡的稳定性。

     

    Abstract: Pre-stressed anchor rods,existing in complex underground environments for long periods,experience performance degradation due to long-term tensile stress and corrosion infiltration. While existing research often focuses on the corrosion of anchor rods under pure environmental factors,there is relatively little analysis on the degradation of mechanical properties under the coupling of stress and corrosive media. This study selects commonly used HRB400 threaded steel anchor rods in engineering as the research object,using the C-ring method constant deformation test to explore the morphological failure characteristics of anchor rod materials under stress-corrosion environments. Additionally,using independently developed stress-corrosion test equipment,the degradation law of the tensile performance of anchor rods under constant prestress and chloride corrosion is investigated. Furthermore,combined with numerical analysis,the study further explores the impact of long-term chloride corrosion environments on the pre-stressed anchor rods for slope support and slope stability. The research results show that in chloride corrosion environments,the surface of the anchor rod body exhibits small cracks and pitting corrosion,with localized accelerated corrosion areas. With the passage of time or the increase of stress,these corrosion pits become more pronounced.Under the combined action of constant prestress and chloride corrosion,although the tensile strength of the anchor rod is slightly reduced,it still meets the specification requirements. However,it is worth noting that the elongation of the anchor rod body after tensioning decreases significantly,approaching the lower limit specified in the standards. Through numerical simulation analysis,it is found that the degradation of the mechanical properties of the anchor rod leads to an increase in slope displacement,tension failure at the top of the slope,and gradual expansion of the shear failure zone. With the increasing degree of corrosion,a slip-through surface may form,significantly reducing the stability of the slope.

     

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