How to make a solid from surfaces

Coreform Cubit Meshing
#1

Hello,
I have created a solid from a topography of a terrain. However, even though it is a solid element in CAD program that i worked on, once I open it in Trelis, in becomes separate 6 surfaces.Can you please tell me how I can make it a solid? It seems there are spaces and overlapping between surfaces and some small surfaces are connected to bottom surface. Some how the system does not allow me to attach the file. Thank you.
Regards,

Muhsin

#2

If the surfaces are sheet bodies, you could stitch them together.

“stitch body all”