The pressure boundary condition for the top surface of the clay layer is initially set to zero to form a permeable surface. When the first embankment layer is activated, however, the pressure degree of freedom at the contact interface between the clay layer and the first embankment layer is deleted for the corresponding nodes to form an impermeable boundary condition.
Displacement of the embankment layers in the Y direction is restrained from motion in the Y direction only when their corresponding elements are deactivated (EKILL). When those elements are reactivated (EALIVE), the zero UY degree of freedom of the embankment layers is also deleted.
As the embankment layers are deactivated and activated, it is also necessary to deactivate and activate the contact-pair elements associated with them.
The only load applied to the model is self-weight, simulated via soil analysis:
Example 52.1: Apply Self-weight Loading
ANTYPE,SOIL ! Set the analysis type to SOIL SSOPT,SFSW,0,-1,0,ON,ON ! Enable specific weight loading and set direction