对锦屏二级水电站防渗墙后止水失效情况下的渗流量、渗流场及渗透稳定等水力特性进行了数值模拟。计算结果表明：止水失效时，防渗墙便会失去作用，护坦段扬压力会增高，护坦段需要布置排水措施；止水失效成空缝时，渗流量剧增，基础将会发生渗透破坏，应对防渗墙后止水措施和工艺加以重视；止水失效但接缝被渗透系数为10-3cm/s量级的淤泥填淤时，渗流量、渗流场及渗透坡降场与止水正常情况时相近。

Seepage simulation was conducted under the condition of water seal failure behind the cut off wall in Jinping 2nd Stage Hydropower Station. The effects of the failure of water seal on seepage discharge, porous pressure and seepage stability were analyzed. The calculated result shows that the seepage control effect of the cutoff wall is lost when the water seal is destroyed, and then uplift pressures at apron and the seepage discharge increase considerably. The apron may be destroyed without drainage measure and seepage damage occurs. However, if the fracture of water seal is filled with silts, in which permeability coefficient is a 10 -3 cm/s magnitude, the hydraulic characteristics are similar to that under normal condition.