Many shallow foundations are built on unsaturated soils and their safety is influenced by uncertainties of soil parameters. By using van Genuchten model to describe soil-water characteristic curves of unsaturated soils, the load-settlement curve is obtained and a uniform limit state function for both the ultimate limit state and the serviceability limit state is proposed. The first order reliability analysis method is used to carry out the reliability analysis of shallow foundations on unsaturated soils under rainfall infiltration, and the influence of rainfall intensity, initial suction and limit tolerable settlement on the reliability of shallow foundation are investigated. Results show that rainfall intensity and initial suction has a large influence on the reliability index of shallow foundation. With the increase of limit tolerable settlement, the reliability index of shallow foundation increases rapidly at the beginning stage of rainfall and then tends to a stable value.
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