应力腐蚀对锚杆使用寿命影响的试验研究

EXPERIMENTAL STUDY ON DURABLENESS OF ANCHOR WITH STRESS CORROSION

通过室内模拟试验和现场取样测试的方式,对比研究应力腐蚀条件下影响锚杆使用寿命的因素。室内试验中自行设计应力腐蚀试验装置,通过砝码在外部对置于腐蚀溶液中的试件加压,使其处在应力和腐蚀协同作用的条件下;现场取样是挖掘17 a前埋设的一批施加不同等级预应力的缩尺锚杆,并对其腐蚀环境和状况进行全面测试。试验结果显示:应力对砂浆缺陷处钢筋腐蚀速度有促进作用,在锚杆上涂保护层比不涂保护层其腐蚀速度降低3～6倍;在中等腐蚀环境下,裸露缩尺锚杆(钢筒体)的平均屈服荷载比原来减小了约50%,极限强度比原来减小了约20%;指出坑蚀普遍存在,坑蚀深度直接影响锚杆的承载力变化,这一点应不容忽视。

The influencing factors on the durableness of anchor with stress corrosion by the way of simulation in laboratory and site sampling are studied.In the laboratory,the test equipment of stress corrosion was designed by the authors,and during the experiment,the sample was put into corrosion solution and gave stress by the external weight to form the stress and corrosion synergies conditions.The sampling site was excavated with a number of scale-reduced anchors that were planted 17 years ago with different levels of prestress.To their corrosion and corrosion status of a comprehensive testing,the test results are shown as follows：（1） stress promotes the corrosion speed of bar which has mortar deficiency,and the corrosion speed of anchor reduce 3-6 times with coat covering layer against that without covering layer;（2） under the medium corrosion circumstance,the average yield load of naked-scaled anchor reduces about 50%,but the ultimate strength of naked-scaled anchor reduces about 20%;（3） pitting corrosion is general existing,and the depth of pitting corrosion direct influences the bearing capacity change of anchor,therefore,it can not be ignored.