为实现桩基础结构安全及其服役状态的监测和有效评估，提出一种双膜结构土压力传感器，以光纤布拉格光栅（fiber Bragg grating，FBG）为传感元件，通过保护结构中增加的温度补偿膜，实现温度作用与外部荷载作用的彻底分离。基于双膜结构土压力传感器的工作原理，讨论了传感器压力灵敏度系数特性。结合有限元分析和实验研究，对灵敏度系数的影响参数展开了系统分析。数值分析结果表明，膜片厚度对压力敏感度系数的影响最大，结构半径和膜片厚度可选取为20 mm和1.8 mm；实验结果表明，在0~2 MPa范围内，压力灵敏度系数达3.32 pm/kPa。
In order to realize the health monitoring and effective evaluation of the pile foundation structure safety and its service state, a double-diaphragm structure soil pressure sensor is proposed in this paper. Fiber Bragg gratings (FBGs) are used as the sensing element. By adding a temperature compensation film in the protective structure, complete separation of temperature effects and external load impacts is achieved. Based on the working principle of a double-diaphragm structure soil pressure sensor, the pressure sensitivity coefficient characteristics of the sensor are discussed. A systematic analysis is conducted on the influencing parameters of sensitivity coefficient by combining finite element analysis and experimental research. Numerical analysis results show that the thickness of the membrane has the greatest impact on the pressure sensitivity coefficient. The structural radius and membrane thickness can be set as 20 mm and 1.8 mm, respectively. Experimental results show that within the range of 0~2 MPa, the pressure sensitivity coefficient reaches 3.32 pm/kPa.
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