High-precision FBG-based sensor for soil settlement monitoring: A comparative study with magnetic settlement gauges and PIV technique

Abstract

The primary objective of layered settlement monitoring is to detect subsidence issues in soil or foundational structures, in order to implement appropriate measures for ensuring the safety and stability of engineering projects. Conventional monitoring techniques have problems such as errors in manual readings, high costs, susceptibility to interference, and low levels of automation. A layered soil settlement sensor based on fiber Bragg grating (FBG) technology is proposed in this study. This sensor utilizes an equal-strength beam as an "intermediate bridge" to make the FBG sensor respond. The sensor is prepared by the laboratory's 3D fused deposition modelling (FDM) and calibrated by applying displacement loads through a fine-tuning platform. The sensitivity coefficient is 0.068 nm/mm, and the correlation coefficient exceeds 0.99. Finally, the sensor exhibited high precision when compared to measurements obtained from magnetic settlement gauges and particle image velocimetry (PIV). The discrepancies between the measurement outcomes of the sensor and the actual values of soil settlement does not exceed 3.33%.