Attenuation Law of Soil Shear Strength During Rainfall Infiltration in Over‐Wet Soil Embankments

This study addresses the critical engineering challenge posed by embankment failures in over‐wet soil, which are susceptible to significant settlement and landslides due to rainfall infiltration. The primary objective is to quantify the reductions in soil shear strength both with depth and over time during rainfall infiltration in these embankments. We introduce the “rainfall infiltration coefficient,” a dimensionless parameter that reflects changes in the Euler number, indicative of the microstructural bonding among soil particles. The coefficient is crucial for understanding the degradation of soil structural integrity under wet conditions. Microstructural tests were performed to establish the relationships between the Euler number and the shear strength of over‐wet soil under varying rainfall infiltration conditions. We applied the Fourier sine transform method to solve the diffusion equation for rainfall in over‐wet soil, deriving a new expression that models the attenuation of soil shear strength relative to depth and infiltration time. Validation of these expressions through comparison with empirical data on rainfall infiltration in over‐wet soil confirms its accuracy and reliability. In conclusion, this study provides validated mathematical models that not only enhance the understanding of over‐wet soil shear strength attenuation during rainfall but also significantly contribute to the design and safety of embankments by enabling accurate predictions of soil strength deterioration under varying rainfall conditions.