FLAC is based on FDM analysis meanwhile Plaxis based on FEM analysis so they inheritance their parent properties. FEM is better for the static problem meanwhile the FDM is better for dynamic problem. Plaxis is better if you want to solve a simple problem in a complex strata. If you want to solve a complex problem as dynamic response of soil-structure in a simplified soil deposit you should better use FLAC.

Thank you sadigh.That was helpful.

What about using explicit method to solve differential equations instead implicit by flac?

Can it make flac better in some aspect or not?

i think FLAC utilizes an explicit finite difference formulation. But what is the numerical problem that you want to solve?

I know FLAC uses the explicit method.my question is which method is more powerful in geotechnical problems generaly:explicit or implicit?