Research on small-sized earth pressure sensor based on ultra-weak fiber Bragg grating

A new earth pressure sensor is constructed based on the inverted triangle and flat diaphragm slotted sensing structure, combined with Ultra Weak Fiber Bragg Grating sensing technology. The influence of earth pressure sensing element size, flat diaphragm thickness and slotted depth on the sensitivity and detection range of the sensor is studied in combination with ANSYS simulation theory, and the theoretical optimal preparation size of the earth pressure sensor is obtained. Based on the principle of flat diaphragm pressure sensing, the innovative pressure-strain sensitization theory of inverted triangular structure is proposed, which will substantially improve the sensitivity of the sensor. A small Ultra Weak Fiber Bragg Grating earth pressure sensor with a diameter of 40 mm and temperature compensation is designed, and the characteristics of the sensor are calibrated using a uniform mechanical loading method of gravity-sand layer-diaphragm. The results show that the sensitivity of the pressure sensor can reach 7.3 pm/KPa with a full scale range of 0.7 MPa, effectively eliminating the effect of temperature on the sensor, and can be connected in series with a distributed ultra-weak grating fiber optic cable to achieve point/distributed sensing.