南水北调东线渠道衬砌混凝土厚度GPR快速无损检测

根据南水北调东线渠道衬砌混凝土两种典型配比制作了不同组分试验样块,利用探地雷达法（GPR）通过实测反射走时计算得到样块介电常数。基于试验结果研究确定了两种配比混凝土符合的介电模型和介电常数随龄期变化特征,给出了混凝土电磁波速模型估算公式,实现了混凝土厚度快速测定。实例证实速度模型公式可直接用于混凝土薄板厚度GPR检测中,检测相对误差小于10%。

No Destructive Testing by GPR method on Thickness of Concrete Channel Lining in the East Route of The South-to-North Water Transfer Project

According to compositions of the two lining concrete used in the east route of South-to-North Water Transfer Project, some concrete samples have been made and teated with GPR to get the reflect time, then the relatively dielectric constants were calculated with their thickness and reflect time. Based on the testing results, representative dielectric models of lining concrete was confirmed, meanwhile the rule of relatively dielectric constant varying with the mixing age also was pointed out. Furthermore the velocity formulae of GPR were made with the composition dielectric of concrete and its volume content. Examples showed the velocity formulae of GPR could be used to calculate thickness of concrete lin-ing well and quickly, the relative error of calculated thickness was under 10%.