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 pres-sure 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 work-ing 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 mem-brane 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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