In designing anti-seepage wall of reservoir’s dam foundation

there always have the inclination of over-security because of lack of testing or just using old analytical method. To solve this problem

this paper based on optimization theory

and by using the 2D finite element method

realized the optimal choice of the thickness and depth of dam foundation’s anti-seepage wall at Yanshan reservoir

in Henan Province. Firstly

the seepage fields of the dam foundations that have anti-seepage wall of different depth and height were modeled. And by comparing the calculating hydraulic gradients and seepage amount with the permissible hydraulic gradients and seepage amount

the optimized anti-seepage has been obtained as follows: the depth is 0.8 m

and the height is 5 m into the fractured area.