基于Richards方程，对坝体的饱和-非饱和渗流场进行了模拟，再根据饱和-非饱和渗流场和非饱和土抗剪强度公式，对坝体的稳定性进行了分析。结果表明，水位骤降过程中坝体的安全系数通常呈现先缓慢增加后迅速减小的变化过程，分析坝体失稳时塑性区和位移场发现，水位下降的初期，坝体左侧坡体的安全系数要低于坝体右侧坡体，但水位下降到一定程度，右侧坡体的安全系数迅速减小，并先于左侧坡体失稳；采用有限元强度折减法用于多坡面边坡稳定分析时，只能获得最小安全系数的包络线；心墙具有隔水防渗的作用，对水位变化渗流具有阻尼作用。

In this study, the Richards equation is employed for the simulation of saturated-unsaturated seepage field; and then the dam stability is analyzed and assessed based on the derived seepage field and the shear strength formulation of unsaturated soil. Numerical results show that the safety factor of dam appears to increase mildly followed by a rapid decrease during the rapid drawdown process of water level. According to the analysis and visualization of plastic zones and displacement fields, it is found that at the early stage of water level drawdown, the left dam slope shall be more dangerous and collapse firstly before the right dam slope; while the water level drawdown exceeds a certain level, the right dam slope shall be more dangerous due to its rapid decrease. One limitation is that only the lowest envelope of multiple safely factor curves can be achieved if of shear strength finite element method is employed for the stability analysis of slope with multiple slope faces. Core wall plays a water-blocking and seepage-proofing role; and it has a damping effect of water level drawdown.