A. NOORZAD - University of Tehran, Iran
B. BANIJAMALI

In this paper, the two-dimensional scattering of plane SH waves by an elliptical cavity (including unlined tunnel) are analyzed. The exact series solution of the problem, for general angle of incidence of the plane SH waves, has been used to examine how the presence of the tunnel amplify the motion. (a) The nature of ground motion has been found to depend on two key parameters: (b) The angle of incidence. (c) The ratio of the tunnel width to the wavelength of incident SH waves. The ratio of length to width of the tunnel. For different length to width ratios, different dimensionless frequencies and various incidence angles, amplitude and phase of the surface displacements are given in Figures 2-6. The maximum displacements amplitude is equal to 4 for the wave propagating with =60. For the bigger values of the tunnel length to width ratio, there are more abrupt jumps in amplitudes and phases.

wave propagation, Matheiu function, cavity, unlined tunnel