分布式光纤传感技术在预制桩基桩内力测试中的应用

分布式光纤传感技术具有分布式和长距离检测等特点,且传感光纤极易植入到成型工程构件中,在线形工程构件的监测和检测中具有独特优势。介绍了布里渊光时域反射计(BOTDR)的传感原理及预制桩传感光纤的植入工艺,给出了基于分布式应变模式下桩身变形和内力的分析方法和计算公式,并结合实例对测试误差来源进行了分析。研究表明:采用开槽粘贴布纤的铺设工艺,实现了预制桩分布式光纤应变测试,可获得桩身轴力、侧摩阻力及桩端阻力的分布特征,简化和完善了预制桩的内力测试工作。测试精度可通过设置参比光纤、提高定位精度、完善铺设工艺及滤波去噪等方法进行提高。

Application of distributed optical fiber sensing to testing inner force of prefabricated piles

The distributed optical fiber sensing technique has unique advantages in monitoring and inspecting of linear engineering,such as long distributed sensing and being easy to be fixed in the molded structures.The basic principle of the Brilliouin optical time domain reflectometer(BOTDR) and the technique to fix the sensing optical fiber in prefabricated piles are presented.The formulas for the distortion and internal force of the piles under the distributed strain mode are deduced,and the test results and the origin of the test error are analyzed through practical examples.The research results show that the pile strain distribution tested by the sensing optical fiber,laid in the prefabricated piles by slotting and sticking it with epoxy,can help to obtain the pile axis force,skin friction,end-bearing resistance and pile bearing features.The test error can be eliminated by setting comparative optical fiber,raising position-setting precision,consummating the sensing techniques,filtering wave,and denoising,among others.