Isolation effect of composite multilayer wave impeding block on P-wave in unsaturated foundation

The traditional wave impeding block (WIB) is designed as composite multilayer WIB with the same thickness to improve its vibration isolation effect. Based on the wave theory in unsaturated porous medium and elastic medium, the isolation effect of composite multilayer WIB on P-wave in unsaturated soil is investigated, and the solution of the vertical displacement at surface after setting composite multilayer WIB (as an example for triple-layer) in unsaturated foundation is obtained. The key factors such as incidence angle, frequency, saturation, thickness, and burial depth of the composite multilayer WIB are evaluated on its vibration isolation properties. The results show that the optimum vibration isolation effect can be achieved by controlling the wave impedance ratio among layers of materials. The isolation efficiency of composite multilayer WIB is 33.9% higher than homogeneous WIB with same thickness at l east, and has good vibration isolation effect for low, medium, and high frequency.