Pressure sensors are the essential equipments in the field of pressure measurement. In this work, we propose a temperature compensation fiber Bragg grating (FBG) pressure sensor based on the plane diaphragm. The plane diaphragm and pressure sensitivity FBG (PS FBG) are used as the pressure sensitive components, and the temperature compensation FBG (TC FBG) is used to improve the temperature cross-sensitivity. Mechanical deformation model and deformation characteristics simulation analysis of the diaphragm are presented. The measurement principle and theoretical analysis of the mathematical relationship between the FBG central wavelength shift and pressure of the sensor are introduced. The sensitivity and measure range can be adjusted by utilizing the different materials and sizes of the diaphragm to accommodate different measure environments. The performance experiments are carried out, and the results indicate that the pressure sensitivity of the sensor is 35.7 pm/MPa in a range from 0 MPa to 50 MPa and has good linearity with a linear fitting correlation coefficient of 99.95%. In addition, the sensor has the advantages of low frequency chirp and high stability, which can be used to measure pressure in mining engineering, civil engineering, or other complex environment.

The bolt support is one of the most important types of active support in anchorage engineering. The anchorage quality of the bolt is directly linked to the safety and stability of the anchorage engineering. Therefore, it is very important and necessary to monitor the stress state of the bolt. Conventional monitoring instruments are susceptible to electromagnetic interference and can not implement remote long-term monitoring and quasi-distributed measurement. A hydraulic-type FBG sensor for axial bolt load measurement is presented, comprising a pressure ring as a load-carrying structure, hydraulic oil as a transfer medium, an elastic diaphragm and a cantilever as sensitizer, and a FBG as the sensing element. The overall structure and working principle of the sensor are introduced in detail, and the theoretical relationship between the FBG wavelength shift difference and the force is established. Accurate force measurement can be obtained by monitoring the two FBGs’ wavelength shift difference. The experimental results show that the average force sensitivity is 39.61 pm kN−1 in the range of 0–100 kN, and the linear coefficient is above 99.88%. The measurement sensitivity is improved by using the wavelength shift difference as the monitoring data, which avoids the cross-sensitive influence. In addition, WDM and SDM technology is adopted for constructing a FBG quasi-distributed measurement system to realize on-line monitoring of axial bolt load. The sensor proposed in this paper has wide application prospects in the field of health monitoring in anchorage engineering.