In seepage analysis with the composite element method (CEM), the drainage holes are looked as some materials with high permeability coefficient and are treated as “air sub-element” set in the conventional rock (soil) element, which is called composite element.

The second infiltration problem in the seepage analysis was solved through increasing a lot of strong permeability air elements on top of covering soil layer.

The drainage hole in the analysis of using air element method to simulate seepage field;

Study and application of unit air filter system;