Breathing Phenomenon of Soil Desiccation Cracking: Insights From Novel Geophysical Observations

Drought-induced soil desiccation cracking is a common natural phenomenon on the earth surface, which plays a significant role in influencing the hydro-mechanical behavior of soils across various earthen engineering applications. However, there is still a scarcity of related studies investigating how field soil desiccation cracking responds to climate action. This study develops an innovative geophysical monitoring framework for investigating field desiccation cracking behaviors by utilizing the distributed fiber optical sensing (DFOS) technique based on optical frequency domain reflectometry (OFDR). The feasibility and significant potential of the DFOS-OFDR framework in advancing soil desiccation cracking research is demonstrated through the implementation of field monitoring tests. The results not only indicate that the strain distribution curves of fiber optic cables at different depths provide insights into the soil shrinkage characteristics and the crack localization capability but also demonstrate the early detection capability of the DFOS-OFDR framework for soil desiccation cracking from a visual perspective. Importantly, the field monitoring tests reveal that under the influence of climate change, desiccation cracking exhibits a distinctive pattern of periodic propagation and narrowing. This intriguing phenomenon is referred to as "soil crack breathing." Additionally, the DFOS-OFDR framework exhibits enhanced sensitivity in sensing the soil crack breathing phenomenon than visual observation methods. This innovative geophysical monitoring framework not only enables real-time observation, continuous measurement, and high-resolution characterization of soil desiccation cracking behavior but also serves as a valuable high-precision observational method for investigating the complex soil-atmosphere interactions under the influence of climate change. Drying and drying-wetting cycles can induce desiccation cracking in field clayey soils, adversely affecting the hydro-mechanical behavior of soils. The challenges posed by desiccation cracks are increasing due to the acknowledgment of climate change as a contributing factor to the heightened severity and frequency of droughts and drought-heavy precipitation cycles, two primary factors triggering soil cracking. However, there is still a scarcity of related studies investigating how field soil desiccation cracking responds to climate action. This study develops an innovative geophysical monitoring framework for investigating field desiccation cracking behaviors by utilizing the distributed fibre optical sensing (DFOS) technique based on optical frequency domain reflectometry (OFDR). The field monitoring tests reveal that under the influence of climate change, desiccation cracking exhibits a distinctive pattern of periodic propagation and narrowing. This intriguing phenomenon is referred to as "soil crack breathing." Moreover, the DFOS-OFDR framework exhibits enhanced sensitivity in sensing the soil crack breathing phenomenon than visual observation methods. The developed monitoring framework can be employed in practice to mitigate the threats that desiccation cracks pose to the integrity of slopes and earthen infrastructure (e.g., levees, earthen dams, landfill covers, roads). Furthermore, the high resolution and accurate characterization of cracks enabled by the proposed monitoring platform will directly contribute toward reducing the risk of several geohazards such as landslides. Field soil desiccation cracking exhibits a distinctive pattern of periodic propagation and narrowing under the influence of climate changeOur field monitoring data provide the first view of soil crack breathing phenomenon to dateThis study marks a significant stride in using innovative geophysical methods to deepen our understanding of intricate natural processes