The Dual Iteration FEM Method to Define the Seepage Free Surface for Non-Darcy Seepage

Darcy Law is the basis of seepage theory for continuum. But there is a lot of Non-Darcy seepage in practical engineering, in the past long time, this type of seepage is used to be simplified into Darcy seepage to analyze. But for some Non-Darcy seepage, if simplified will bring out great errors, such as the seepage in rock-filling dam. Rock filling dam body seepage problem is a Non-Darcy seepage problem with a seepage free surface, which is a seepage dual non-linear problem. It is seepage non-linear problem on configuration relation and seepage non-linear problem on area. Here the dual iteration method is used to solve this seepage problem, and defining the seepage problem, the fixed net method is used. Through the results, the following conclusion can be drawn: (1) The seepage configuration relation is very important to seepage analysis; (2) Rock-filling dam body seepage analysis is dual non-linear problem, is more complex than either single seepage non-linear problem; and the dual iteration method used to solve it is more complex than either single iteration. (3) The free surfaces for Non-Darcy seepage in rock-filling dam and for simplified Darcy seepage have great differences, it is essential to do the Non-Darcy seepage analysis for this type of seepage.