The 12th International Conference on Scour and Erosion (ICSE 2025)

Internally unstable soil, specifically underfilled gap-graded soil are prone to suffusion, a mechanism of internal erosion where fine particles migrate under hydraulic flow. Over time, suffusion results in the gradual washout of finer particles, which can ultimately lead to structural failure. Conventional techniques for suffusion assessment rely on laboratory-based stability criteria, which are effective but invasive and does not provide real time monitoring. This study explores the potential of geoelectric measurements as a non-invasive alternative to identify internally unstable soil and differentiate between underfilled and overfilled fabric. Direct Current (DC) resistivity measurements were conducted on sand-gravel mixtures with 20% and 40% finer fraction. Two key geoelectric parameters, formation factor and surface conductivity, were calculated. These parameters are essential for understanding the electrical properties of the soil mixtures and were correlated to conventional soil parameters. The results showed that geoelectric parameters can effectively differentiate between underfilled and overfilled fabric. Moreover, the findings exhibit a high degree of repeatability, indicating reliable measurements. These results provide a solid foundation for the potential application of geoelectric measurements as a non invasive method for monitoring suffusion.