The deformation resulting from the presence of a tunnel may signifcantly affected, nearby structures and need to be considered during design of both tunnel and structure._x000D_
The aim of this paper is to study the effect of different factors which may affect the interaction between the tunnel and the str- ucture. These include; the depth of both tunnel and foundation level of the structure ( z and t ), distance between C.L. of tunnel and loads, breadth of the loaded area, Diameter of tunnel and lining of the tunnel._x000D_
The problem is studied as a two dimensional plane strain model by the boundary element technique. The results of this study indicated that the presence of a cavity/tunnel increases, in general, the vertical displacement on the ground surface and at the foundation level as well as the horizontal and vertical stresses in the cavity/tunnel level. The effect of eccentricity is increasing as e/D decreasing._x000D_
For pile foundation there is a quite different- influence of the presence of cavity/tunnel in both cases of friction pile and end bearing pile type of foundation.