地震和降雨的时序关系对边坡的稳定性具有显著影响，为了探明降雨-地震时序作用对边坡动力响应及变形失稳的影响机理，通过12组砂质粘土土样的空心圆柱扭剪试验，分析了降雨-地震时序作用下砂质粘土土样剪应力和体应变的变化规律，研究发现降雨-地震时序作用对砂质粘土的极限剪应力影响显著，尤其是震后降雨条件下的影响更为明显；体应变分别出现了负方向性和负摩擦力现象，从而会影响土体的变形和承载能力；在此基础上，以边坡永久位移和滑移面为边坡动力损伤破坏的定量评价指标，重点研究了震后降雨作用下砂质粘土边坡的动力响应及变形失稳机理。研究结果表明：降雨之前有无震动损伤，对边坡内部地下水位的上升速度有较大影响，边坡会呈现出不同的变形失稳破坏模式；不同等级地震作用下边坡损伤程度不同，后期降雨时边坡的滑移面形状、滑移规模、剪出口位置不同，但是整体表现为在边坡某一高度位置形成拉裂缝，随着降雨的持续作用拉裂缝逐步向坡脚底部逐级扩展，并产生滑移破坏，最后在坡脚形成堆积体。所得结论可为类似工程问题中边坡稳定性评价和防护提供理论依据以及技术支撑。

The sequential relationship between earthquakes and rainfall significantly influences slope stability. To elucidate the influence mechanism of dynamic responses and deformation and failure of slope under rainfall-earthquake sequential effects, we carried out hollow cylindrical torsion tests of 12 groups of sandy clay samples and attempted to analyze the variation rules of shear stress and volumetric strain of these samples with axial strain under rainfall-earthquake sequential effects. It was observed that the sequential effects significantly influenced the ultimate shear stress of sandy clay, especially under post-seismic rainfall conditions. Volumetric strain showed negative directional and negative frictional behaviors, which would affect the deformation and load-bearing capacity of soil body. Based on these observations, we mainly studied influence mechanism of dynamic responses and deformation and failure of slope under rainfall-earthquake sequential effects by taking the permanent displacement of the slope and the slip surface as quantitative evaluation indicators of dynamic damage and failure of the slope. The results showed that the presence or absence of seismic damage before rainfall could greatly affect the rising speed of underground water level inside the slope, which would lead to various deformational failure modes. The results also showed that the damage of slopes vary with earthquakes of different magnitudes, and hence the shape, scale, and shear exit location of the slip surface vary as well during subsequent rainfall. However, the damage is generally showed as tension cracks at a certain height on the slope. With sustained rainfall, these cracks gradually extend downwards the base of the slope, leading to sliding failures and eventually resulting in accumulation body at the base. The findings could provide theoretical and technical support for slope stability assessment and protection in analogous engineering problems.