Abstract：To investigate the impact of rainfall patterns on the infiltration and stability of unsaturated soil slopes, a coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) analysis was conducted during rainfall infiltration. This analysis utilized the Finite Volume Method (FVM) and the Python solver FiPy. Comparisons with experimental results from model tests on granite residual soil slopes facilitated the calibration of micromechanical contact parameters in the discrete element simulation. The study examined variations in moisture content, particle displacement, and slip surfaces of granite residual soil slopes under four rainfall patterns: front-type, middle-type, uniform-type, and rear-type. The results indicate a strong correlation between the simulated and experimental data regarding infiltration rates, displacement changes, and slope failure modes, thereby confirming the effectiveness of this methodology. Rainfall patterns had a significant impact on the displacement and rotation of slope particles, particularly under front-type rainfall conditions, where the moisture content of the slope increased rapidly, accompanied by sharp rises in particle displacement and rotation, ultimately resulting in a translational failure of the entire slope. The influence of different rainfall types on slope stability is ranked from most to least significant as follows: front-type, middle-type, rear-type, and uniform-type. Slope failure initiated from cracks at the base of the slope and progressively extended upward until a complete slip surface was established. Initially, cracks were predominantly concentrated in the range of 105°to 135°, whereas, following the total failure of the slope, most particle contact fractures occurred in the direction of 90°to 120°.
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2025, Vol. 44 
