I am working with a dynamic problem using PLAXIS 3D. When I select viscous boundary at base, standard fixities do not work any more at base, even after selecting fully fixed in deformation menu. As a result, my soil model moves downward after dynamic calculation and also expected pattern of results are not obtained in this case. What can I do to imply both boundary condition?
Again, if I want to use only standard fixities at base, what should be the minimum distance of base from dynamic loading source?