Structural design verifications, structural analysis of tunnels - Tunnel Engineering: Basics and Additional Services for Design and Construction - page 108

and the weaknesses can be compensated. The inner, plastic zone is modelled using FEM and
the outer, elastic layer using BEM. The advantage is that the discretisation and calculation
time is relatively low despite the good representation of the real conditions (Fig. 3-10).
Figure 3-10 Discretisa-
tion example for the
Boundary Element Method
(REM).
Fig. 3-11 shows a typical application. The inner, geometrically complex zone is discretised
with the finite element groups A, B and C. The rock mass into infinity is modelled by the
boundary element group D.
Figure 3-11 Combined finite element /
boundary element mesh [18].