为了揭示膨胀岩边坡破坏机理，采用流固耦合的非线性有限元分析方法，对膨胀岩边坡降雨失稳现场试验进行了数值模拟研究，改进了膨胀岩边坡稳定分析技术，使之能考虑膨胀岩的膨胀性、裂隙性，以及非饱和膨胀岩的吸湿软化特性。数值计算结果表明:非饱和膨胀岩的吸湿软化特性是膨胀岩边坡渐进性破坏的主要原因，膨胀性进一步加剧了这种影响；大气影响带膨胀岩的风化和干湿循环影响导致的浅层裂隙，是膨胀岩边坡浅层滑动的根源。

In order to study the failure mechanism of expansive rock slope under rainfall, on the basis of a non-linear finite element method considering fluid-solid coupling, the numerical simulation on field test of expansive rock slope failure under rainfall is carried out, the stability analysis technology is improved, which considers the expansion and crack characteristics and material softening characteristic by absorbing water. The numerical result shows the material softening characteristic by absorbing water is the main reason causing the progressive failure process of expansive rock slope, and expansive characteristic can intensify this effect. A shallow crack which is caused by weathering and dry-wet cycle is the source of shallow slide of expansive rock slope.