海岛环境条件下超长灌注桩温度光纤监测研究

Study on the Temperature of Super Long Cast‑in‑place Pile on the Island Using Optical Fiber Sensing Technology

为了弥补传统监测手段的不足,更好地掌握海岛环境条件下超长灌注桩温度分布规律,采用了布里渊光时域反射(BOTDR)技术,在海岛环境条件下将光纤温度传感器安装在灌注桩上,对气温变化下116 m长的灌注桩进行了长期温度监测试验。监测结果表明:本次用于超长灌注桩桩体温度测量的光纤传感器均存活,说明传感器布设工艺的合理性,同时从测试结果来看,光纤温度传感器基本上没有受到外力的干扰;采用DB5小波对光纤测试数据进行降噪;从桩体温度变化曲线来看,海岛环境条件下的超长灌注桩桩体温度变化非常复杂,桩头位置温度变化量最大,随着深度增加,温度变化量逐渐减小,至18 m深度处温度基本不发生变化;桩体温度场的变化存在时间效应。

In order to make up for the shortcomings of traditional monitoring methods and understand the temperature distribution of super long cast-in-place piles on the island,the Brillouin optical time domain reflectometer technology(BOTDR)is used,the optical fiber temperature sensor is fixed on the cast-in-place pile,and the temperature of the 116m long cast-in-place pile under the air temperature fluctuation is measured by long-term monitoring in this paper.The monitoring results show that:the optical fiber sensors used for the temperature monitoring of the super long cast-in-place pile all survived,indicating the rationality of the sensor layout method.It can be inferred from the monitoring results that the optical fiber temperature sensor is not disturbed by external forces;the DB5 wavelet is used to reduce the noise of the optical fiber data.From the pile temperature curve,the temperature change of the super long cast-in-place pile on the island is very complex,the temperature change at the pile head is the largest,and it decreases gradually with the depth.At a depth of 18 m,the temperature does not change,the pile temperature has a time effect.