Expansive soil slopes can become unstable when rain seeps in, weakening the soil's suction and strength. A study on a rail transit line in Hefei used software to analyze how rainfall intensity, duration, soil cracks, and time affect slope stability. Results show that prolonged weak rainfall has a big impact, soil cracks decrease stability, and rainfall's influence is ongoing. Among hydraulic factors, saturated hydraulic conductivity (Ksat) is the main player, while other parameters are less important.