Isolation effects of S-wave by composite multilayer wave impeding block in unsaturated soil

Abstract

Based on the propagation theory of elastic waves in unsaturated porous medium and single-phase elastic medium, considering that a composite multilayer wave impeding block (WIB) with a certain thickness is set in unsaturated soil, and using Helmholtz vector decomposition theorem, the analytical solutions of transmitted/reflected amplitude ratio of S-wave passing through the composite multilayer wave impeding block in the unsaturated foundation are derived. The influences of physical and mechanical parameters such as wave impedance ratio, saturation, shear modulus and density of the wave impeding block on the propagation characteristics of S-wave passing through the composite multilayer wave impeding block in unsaturated foundation are analyzed by numerical examples. The results show that the saturation has little influence on the transmission/reflection coefficient of P1-wave and S-wave, but has a significant influence on the transmission/reflection coefficient of P2-wave and P3-wave. The wave impedance ratio and shear modulus of interlayer wave impeding block material have a significant influence on the transmission/reflection coefficient. The best vibration isolation effect can be obtained by selecting the optimal wave impedance ratio and shear modulus of interlayer wave impeding block material, which may be provide a design criteria for the application of composite multilayer wave impeding block in foundation vibration control.