Tunnel lining can be modelled as a beam in PLAXIS 2D and as a plate in PLAXIS 3D. By using this element, 3 types of deformations are taken into account: shear deformation, compression due to normal forces and obviously bending. This document describes an example that has been used to verify the shell elements in PLAXIS.
Bending of axisymmetric plates
Bending of plates
Shear deformation in structural elements
Non-linear deformation of structural elements