基于光纤检测技术的夹泥灌注桩模型试验

将分布式光纤传感技术用于夹泥灌注桩定量检测。建立了加热光纤与桩身介质的单层圆筒壁一维传热模型，利用桩体中光纤的温升变化规律检测夹泥桩的含泥量。开展含泥量分别为0、33.3%、50.0%、66.7%、100.0%的夹泥桩光纤检测模型试验，确定合适的加热功率范围和加热时间，并对光纤传感器进行标定，研究不同夹泥桩中光纤温升变化情况和桩身介质导热系数，发现在相同加热功率下，随着含泥量增大，光纤温升速率变快、增加幅度变大。进一步分析表明，含泥量与桩身介质导热系数之间存在确定的线性关系，并推导出两者数量关系式。通过声波检测对比试验，分析了该技术的测量精度。结果表明，桩体含泥量大于10%时，光纤检测法的精度与声波检测法较为接近。通过以上研究，为定量检测灌注桩的完整性提供了一种思路。

Model test on detection of intercalated mud bored pile using optical fiber sensing technology

Distributed optical fiber sensing technology was applied to the quantitative detection of intercalated mud bored pile. One dimensional model was proposed to simulate the heat transfer of single-layer cylindrical wall made up of heating fiber and pile body medium . Mud content of pile was detected by the variety of temperature rise of optical fiber in the pile. Intercalated mud pile model tests of optic fiber detection were designed with the mud contents of 0, 33.3%, 50%, 66.7% and 100%. After the calibrating of fiber optic sensor, the temperature rise and thermal conductivity coefficient of piles were investigated under appropriate range of heating power and heating time. It was founded that the rate of temperature rise of the fiber was increased with the mud content under the same heating power. Further analysis showed that there is a good linear relationship between mud content and thermal conductivity coefficient of pile. At last, the accuracy of this technique was analyzed by acoustic wave test. The results showed that the accuracy of optic fiber detection method is close to that of the acoustic wave detection method when the mud content of pile is more than 10%. This studies provided a way for quantitative detection of pile integrity.