Abstract: 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.

Key words: optical fiber sensing, intercalated mud bored pile, detection, mud content