Underground modelling

[paololo]

Hello i'm doing a school project and i have to model the underground part of the builind, so the walls and slabs that are in contact with the ground. I saw a lot of suggestions reguarding this topic but i have one last doubt. Do i have to change either the adjacency of the walls to put the t profile f the gorund, and use the ground-contact function toghether? Or i have to choose between one of the two procedures to simulate the contact of the wall to the ground?