Study on the Quasi-Distributed Monitoring Method of Earth Pressure Based on the Thermomechanical Coupling

Conventional measurement methods of Earth pressure have shortcomings, such as narrow coverage of measurement points and influence on the Earth pressure distribution pattern. Based on the correlation between the thermal resistance of a material and its thickness, the surface heat source method for quasi-distributed monitoring of Earth pressure was proposed in this article, and an Earth pressure monitoring system consisting of a surface heat source, a heat-conducting plate, a flexible pad, and a temperature sensing system was developed. First, the effects of the thickness of the flexible pad on the temperature response on the outer surface of flexible pad was investigated by numerical simulation, the relationship between the initial heating rate and the thickness of the flexible pad was established, and the feasibility of the Earth pressure monitoring method proposed in this article was verified by thermomechanical coupling analysis. Then, polyurethane sponge was used as the flexible pad material, and the thermomechanical coupling calibration test was carried out by using the fiber Bragg grating (FBG) temperature sensing system. The results show that the testing results of the temperature response law are basically consistent with the numerical simulation results, and the Earth pressure is linearly related to the initial heating rate. Finally, the influencing factors affecting the sensitivity of Earth pressure measurement were discussed.