Abstract:To the unsaturated-saturated seepage field with densely-distributed drainage holes existing in the computational domain,the drainage substructure is introduced. The involved formulae are deduced and the computation program is developed. Meanwhile,rainfall infiltration and precise simulation of the exit face of the saturated-unsaturated seepage are also introduced. Finally,the problem of the slope seepage field of the permanent shiplock of the Three Gorges Project is calculated. The effectiveness and propriety of the seepage control measures in the slope are analyzed and verified.