基于冲击回波厚度频率的预应力孔道注浆状态分析

Analysis of tendon grouting state based on impact-echo thickness frequency

应用冲击回波法检测预应力孔道的注浆质量时,无浆孔道处厚度频率的确定至关重要。建立三维有限元模型,对影响无浆孔道处厚度频率的多种因素,如孔厚比(波纹管内径与板厚之比)、波纹管类型、壁厚比(波纹管壁厚与板厚之比)等进行了数值分析。提出了无浆孔道处厚度频率的计算公式,并以实验结果验证了分析的有效性。结果表明:无浆孔道处的厚度频率只与孔厚比有关,与板厚无关,且随孔厚比的增大而减小;铁皮波纹管对无浆孔道处厚度频率的影响更显著;当孔厚比及波纹管类型相同时,壁厚比越大,无浆孔道处厚度频率相对于无缺陷板厚度频率的偏移量越大。

It’s important to determine the thickness frequency above ungrouted ducts when applying impact echo method to detect grouting quality in posttensioned bridge ducts.By establishing a 3D finite element model,taking into account the various factors,such as the hole thickness ratio（the ratio of inside diameter of duct to plate thickness）,the duct type,the wall thickness ratio（the ratio of duct wall thickness to plate thickness） and so on,can influence the thickness frequency above ungrouted ducts.A calculation formula for the thickness frequency above ungrouted ducts is presented,and the efficiency of the analysis is shown by experimental results.The results show that： the thickness frequency above ungrouted ducts is regardless of plate thickness,which is related to the hole thickness ratio,and decreases as the hole thickness ratio increases.Both steel and plastic ducts would increase the shift in thickness frequency above ungrouted ducts,but the steel ducts has a significant effect on the shift in thickness frequency.For the same hole thickness ratio and duct type,the shift in thickness frequency above ungrouted ducts is positively correlated with the wall thickness ratio.