Abstract
Soils of which the ground is composed, have been idealized as monophase medium such as elastic, elastoplastic or viscoelastic one, but in reality, they have microscopic structure which consists of solid particle skeleton and fluid saturated in voids. In order to pursue dynamic properties of such a ground that has multiphase structures, it is indispensable to describe real soil structures in detail. Here in this paper, fluid saturated soil layers are analysed as being composed of two-phase mediaelastic solids and water as fluidand then the effect of water in soil on the vibrational mechanisum of the ground is discussed, by computing frequency responses, free vibrations and wave propagation problems of that system. The method of analysis of wave propagation theory of two-phase media in multi-layered system is developed, and simultaneously finite element method in composite material is used comparing with it. Applying to BIOT's constitutive equation for fluid saturated elastic solid, the dispersion relation for composite structures in dynamic case is used as the constitutive relation when frequency response is analysed. A single two-phase soil layer on impermeable base rock is analysed, and numerical experiments are carried out. Results obtained are summarized as follows (1) The effect of water existance in soil layers ground is revealed to damping action in frequency response by interaction of solid fluid mixtures. (2) Proposed method of analysis for two medium structure is compared with finite element analysis. Correspondence is fairly good and it is understood in valid for the analysis of composite soil ground.
