Monitoring and early detection of soil desiccation cracking using distributed fibre optical sensing

Abstract

Desiccation cracking can significantly affect the hydro-mechanical behaviour of soil in various engineering applications. Characterising the evolution of desiccation-induced shrinkage strain in soils is a key step in understanding the cracking mechanism. This study presents a novel framework for monitoring and early detecting soil cracking by utilising the distributed fibre optical sensing (DFOS) technique based on optical frequency domain reflectometry (OFDR). DFOS-OFDR was integrated into a set of experimental testing to simultaneously monitor water content, crack pattern and strain state. OFDR with 1 με strain measurement accuracy was employed to monitor the initiation and propagation of cracks. The results reveal a strong correlation between the spatiotemporal evolution of soil strain and crack, confirming the efficacy and reliability of the proposed framework. During the drying process, the compressive strain induced by soil shrinkage increases first and starts to decrease when cracking is initiated. Further, DFOS-OFDR demonstrated promising results to predict the position of cracks. Compared to traditional strain monitoring methods with discrete measurements, DFOS-OFDR offers a non-destructive, accurate yet efficient, high-resolution and continuous technique for monitoring and early detection of soil desiccation cracking.