基于光纤光栅技术的预应力孔道注浆密实性研究

Study on Grouting Compactness of Prestressed Duct Based on Fibre Bragg Grating Technology

摘要:

为了研究金属波纹管注浆密实性大小，采用光纤光栅检测技术对6种不同注浆缺陷（包括无缺陷和缺陷率为7%、10%、13%、16%、100%的共6种工况）进行现场检测，将密实管和空管作为对照组。通过验证检测结果与设置缺陷的一致性，经过解调仪采集在不同注浆时间（包括初始、10 min、180 min、1 440 min的共4个时刻）的光纤光栅轴向应变来分析密实程度，然后用轴向应变反推光纤光栅中心波长变动量值情况。研究结果发现：对于注浆密实部位应变变化较小，缺陷部位应变变化明显，应变变化随着缺陷率的增大而减小；在注浆180 min时应变变化值最大，占注浆10 min和1 440 min应变变化值之和的60%以上；孔道密实性检测结果与缺陷设置处具有较高的一致性，光纤光栅中心波长变动量随着孔道变形越大越显著。

Abstract:

To study the grouting compactness of metallic bellows, the fiber bragg grating (FBG) technology is adopted to carry out the on-site detection for six different grouting defects (including six different conditions with no defects and defect rates of 7%, 10%, 13%, 16% and 100%). Fully grouted pipes and empty pipes are served as control groups. By verifying the consistency between detection results and preset defects, the axial strain of the FBG at different grouting time (including the initial, 10 min, 180 min and 1,440 min, a total of four moments) is collected by the demodulation instrument to analyze the compactness, and then, the variation value of the central wavelength of the FBG is inversely deduced using the axial strain. The research findings reveals that for the grouting dense parts, the strain variation is relatively small, while for the defect parts, the strain variation is obvious. The strain variation decreases as the defect rate increases. The strain change is the greatest at 180 min of grouting, which accounts for more than 60% of the sum of the strain change values at 10 minutes and 1,440 minutes after grouting. The detecting results of the duct compactness have a high consistency with those at the defect settings. The variation of the central wavelength of the FBG becomes more significant as the deformation of the duct increases.