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Nowadays the tunnels have a main role in daily activites of countries, so the must be designed in a
manner that resist under all static and dynamic loads. In this paper, a deep tunnel in an elastic medium under plane strain condition and
harmonic waves has been studied.
The Boundary Element Method (BEM) in the case of infinite medium is more suitable than
other numerical methods; because the unknown parameters of problem are only on its boundary
and each arbitrary shape of boundary can be modeled easily, furthermore radiation condition
(due to infinite medium) will be satisfied. Hence, the method of analysis is based on Boundary
Element
Method in

unlined
tunnels
and
combinaton of Boundary Element Method and Finite Element Method in lined tunnels.
Results show that stress conentration along the boundary of tunnels due to scattering is about 2 to
3 times greater than the free field stresses imposed by incident wave. As the scattering is due
to the interaction between soil and tunnel, hence this effect should be considered. By parametric
study the effects of types of waves including P and SV waves, the angle of incident wave and the
different shapes of the tunnel are included in this
paper.