An early warning model for desiccation-induced cracking of clay based on OFDR monitoring

Abstract

Desiccation-induced cracking is a critical factor contributing to the occurrence of various hydrological, agricultural, geotechnical, and geological hazards. Therefore, monitoring and early warning of volume shrinkage and tensile failure caused by desiccation in cohesive soils are of paramount importance. In this study, an early warning model is proposed for the desiccation-induced cracking of soil based on optical frequency domain reflectometry (OFDR). The early warning model accounts for the impact of evaporation heterogeneity on moisture content and the curling effect caused by boundary constraints. Design of pullout and drying tests to validate the scientific robustness of the model. A strong correlation is found between soil strain and the temporal evolution of cracks. The early warning model predicts potential cracking zones based on the monitored strain and stress fields. The real-time strain field monitoring is conducted using OFDR technology. The early strain field exhibits a saddle-shaped distribution due to the effects of evaporation heterogeneity and boundary conditions. Early warning of potential cracking zones is achieved by identifying regions with abnormal strain increments. The stress field is determined based on the theoretical framework of the early warning model. During the drying process, tensile stress accumulates in the soil. Cracking occurs when this tensile stress reaches the maximum tensile strength of the soil. By analyzing the distribution of the soil stress field, potential cracking zones can be effectively identified. The model provides valuable insights for real-time monitoring and early warning of soil desiccation, with the potential to advance disaster prevention strategies.