A novel method for earth pressure distribution measurement via the thermo-mechanical response of flexible cushions

Abstract

The compression deformation of a flexible cushion will lead to a decrease in thermal resistance. Based on this characteristic, a surface heat source method for earth pressure monitoring was proposed in this paper. In this method, a surface heat source, a heat-conducting plate, a flexible cushion, and a temperature sensing array were sequentially placed on the surface of the structure under test. The pressure distribution can be identified by monitoring the temperature response on the outer surface of the flexible cushion after the surface heat source was electric heated. Firstly, a series of calibration tests were conducted on two kinds of flexible cushions made of polyurethane sponge pad and silicone foam board under uniform compression. A dimensionless pressure discrimination index κ was defined based on the heating law on the outer surface of the flexible cushion, and the calibration relationship between pressure and κ was established. The effects of thickness and material properties of flexible cushion on the measurement sensitivity and range were also studied. Then, a polyurethane sponge pad was used as flexible cushion to conduct a series of verification tests under 9 loading conditions. Subsequently, the pressure distributions were identified using the aforementioned calibration relationship between pressure and κ. The results show that the pressure distribution identification results were basically consistent with the actual loading situations, thus verifying the feasibility of the method proposed in this paper.