Numerical Analysis of Wave Propagation in Two-Phase Soil Medium

The paper deals with the problem of dynamic consolidation of two-phase soil medium. Finite Element approach is used to calculate tangential stresses and pore pressure and what follows to describe the wave propagation. Biot's formulation, with so called u - p simplification and Pastor — Zienkiewicz Mark III constitutive relation, is implemented. This model, which treats the soil as an inelastic skeleton saturated with a pore fluid is very close to real behavior of non-cohesive soil under dynamic excitation. Numerical analysis mentioned, is used not only to obtain the result but also to assess them. Cohesion, friction angle and other geotechnical parameters are taken from laboratory tests. Different records of real vibrations along with artificial impulse wave is applied as dynamic loading. Constitutive relations are fully nonlinear and depend on soil type. From numerical calculation we obtain the diagonal shear stress bands which form the typical crosses and pore pressure which responds even after fade of input, proving liquefaction phenomena. The signal processing tool such as Fourier and wavelet transform is used to analyze the results. Two important information such as the time when dominant frequency is reached and the frequencies which are filtered, are retrieved only from wavelet analysis.