Numerical investigation of rainfall-induced shear crack propagation in railway embankment slopes

Slope failures, particularly in railway embankments during intense rainfall, are a major cause of economic damage and humanitarian loss. To forecast how shear cracks develop in slopes under heavy precipitation, we present a novel modeling framework: the Extended Cohesive Damage Element enhanced by soil moisture (SMECDE). The method first translates forecasted rainfall into soil moisture levels via an established correspondence. Then, recognizing that rainfall infiltration lowers soil cohesion-particularly at varying depths-we introduce a Soil Moisture Decoherence Model (SMDM) based on experimental data, which quantifies how cohesion degrades with moisture and how depth affects this process. By embedding SMDM within the ECDE technique, we investigate how shear fractures propagate under different moisture conditions throughout the slope profile. We apply SMECDE to a real railway embankment case to identify critical moisture thresholds and crack growth patterns. Validation is performed by comparing predictions against field measurements and weather station records, and further checked through simulations of large-scale plastic deformation in ABAQUS.