水环境下植筋试件粘结界面的劣化规律

为研究植筋试件的粘结界面在各劣化环境下的劣化规律,进行了周期为1年的单筋拉拔试验。试验考虑了2种植筋深度、7种劣化方案和5种劣化时长,共制作了280个试件。通过正交试验的方法实测了植筋试件的破坏形态和极限荷载,绘制了荷载-劣化时长曲线。试验结果表明,表面+侧面约束下,植筋试件破坏形式最为理想,受力情况最好,破坏发生在胶-混凝土界面;多种劣化因素作用下,泡盐水与持载耦合环境的试件其最大承载力下降程度最大;当植筋深度为120 mm、劣化时长为1年时,相对于室内干燥环境其最大承载力下降了53. 8%;对比单因素、双因素耦合以及三因素耦合情况下的最大承载力,可知水环境、氯离子、持续荷载的耦合作用对胶-混凝土界面的劣化作用最强;劣化时长相同时,植筋深度h在一定范围内,h越大植筋的最大承载力越大;室外环境下,最大承载力的衰减速率|k|呈现出季节性变化,夏冬两季的|k|值明显大于春秋两季。

Deterioration Laws of Bonding Interface of Chemical Planted Rebars under Water Environments

In order to study the deterioration laws of bonding interface of chemical planted rebars under various deteriorating environments, a one-year pull-out test was carried out. Two planting depth, seven deterioration schemes and five deterioration time were considered in this experiment. A total of 280 specimens were made. By using orthogonal test method, The failure modes and ultimate loads of the specimens were measured, and the load-deterioration time curve was drawn. The test results show that under the surface + side restraint, the failure mode of the specimens is ideal, the stress condition is the best, and the failure occurs at the adhesive-concrete interface; The maximum bearing capacity of specimens under brine and sustain load coupled environment is the highest. When the planting depth is 120 mm and the deterioration time is 1 year, the maximum bearing capacity decreases by 53.8% compared to indoor environment; Comparing the maximum bearing capacity of single-factor, double-factor and three-factor coupling, it can be concluded that the coupling effect of water environment, chloride ion and sustained load has the strongest deterioration effect on the adhesive-concrete interface; When the time is same and the depth of planting bar(H) in a certain range, the greater the H is, the greater the maximum bearing capacity of planting bar will be; in the outdoor environment, the decay rate of the maximum bearing capacity shows seasonal variation, and the value of |k| in summer and winter is obviously larger than that in spring and autumn.