索体腐蚀对锚索结构锚固性能的影响

Effects of Cable Corrosion on Anchoring Behavior of Anchor Cable Structures

为了给侵蚀环境下锚索结构长期锚固性能评估与设计提供参考,考虑锚固受力时的围岩约束因素,设计制作了外包钢管圆柱形素水泥浆中置钢绞线短黏结试件模拟锚索结构单元,采用直流通电方式使钢绞线实现5%、10%和15%三个不同程度的腐蚀率,然后通过静力拔出试验观察锚固受力过程,获取黏结-滑移曲线,定义锚固特征参数,分析腐蚀对锚固性能的影响规律,建立黏结-滑移本构关系经验模型。结果表明:围岩约束显著提高了锚固强度和延性性能;腐蚀程度对黏结-滑移曲线特征产生很大影响;与无腐蚀锚索相比,当腐蚀率小于15%时,腐蚀锚索锚固强度最大可提高至2.5倍左右,但正常工作刚度和延性指数则可分别降低至12%和0.32%左右。

To provide references for evaluation and design of long-term anchoring behavior of anchor cables served in erosion environment,considering the restriction effect of surrounding rock in the mechanical condition of anchoring,a kind of short-bonded specimen of plain cement slurry cylinder wrapped by steel pipes outside and permeated by steel strands centrally was designed and fabricated to simulate structural unit of anchor cable structure.The steel strands were then corroded by galvanostatic method to achieve three level corrosion rates of 5%,10%and 15%.A static pull-out test was executed to observe the anchoring bearing process,obtain the bond-slip curves and define the characteristic anchoring parameters.Then the influence law of corrosion on anchoring behavior was analyzed and the empirical constitutive relation model of bond-slip was built.The results show that the restriction of surrounding rock significantly improves the anchoring strength and ductility.The character of bond-slip curve is affected evidently by corrosion degree.Compared with uncorroded anchor cables,when the corrodedanchor cables have a corrosion rate below 15%,the anchoring strength may increase to nearly 2.5times of it while the service rigid and ductile index may decrease to about 12% and 0.32%respectively.