Impedances for Radially Inhomogeneous Viscoelastic Soil Media

The dynamic impedances of a radially inhomogeneous viscoelastic soil layer with a central hole are formulated based on a new boundary zone model with a nonreflective boundary. A parabolic variation of the medium properties is assumed, so that the boundary zone has properties smoothly approaching those of the outer zone to alleviate wave reflections from the interface between the two media. Vertically, torsionally and radially excited soil layers have been examined in this paper. The results are evaluated over a wide range of the parameters involved and compared with those obtained for a homogeneous layer, as well as compared with Novak and Veletsos's solutions. Since this boundary-zone model includes mass and a nonreflective boundary, the impedances (soil stiffness and damping) presented in this paper are considered to be more suitable to practical applications.