Use the Predeformation subnode to specify that the elastic forces in Spring Foundation or Thin Elastic Layer are non-zero at zero displacement. Thus you can model cases where the unstressed state of the spring is in another configuration than the one described by the geometry.

Based on space dimension, enter the values for the Spring Predeformation u0.

Physics tab with Spring Foundation or Thin Elastic Layer node selected in the model tree:
Attributes>Predeformation