A multi-node finite element method for numerical simulation of unconfined seepage flow through porous media is presented. Using multi-node elements to approximate the free surface of seepage

the shape functions of multi-node elements are constructed by mean value interpolation. The quadrilateral/triangle elements are used to partition the remainder domain far from the free surface. Giving an initial location of free surface and solving governing equation of unconfined seepage flow problem by multi-node finite element method

according to water head value of nodes on free surface to adjust the location of nodes

the final location of free surface is obtained by iteration technique. Numerical analysis of seepage problem of earth dam shows validity and accuracy of the method.