Abstract: Based on the research of unsaturated porous media, the propagation characteristics of Rayleigh waves in unsaturated soil are studied by considering the interaction between liquid and gas phases in the pores. The elastic wave equations are established using the mass balance equations, the momentum balance equations and the effective stress principle of the unsaturated soil. The dispersion equations of Rayleigh wave in unsaturated soil are derived by introducing potential functions and combining free permeable and breathable boundary conditions. Finally, the effects of saturation degree, frequency, and intrinsic permeability coefficient on the wave velocity and attenuation coefficient are discussed by numerical examples. The results show that the trend of wave velocity is first unchanged with the frequency and inherent permeability coefficient, then decreases slightly, then increases sharply, and finally becomes consistent at different saturations. Moreover, the attenuation coefficient first increases with the increase of frequency and then decreases with the increase of the intrinsic permeability coefficient at different saturations.

Key words: unsaturated soil, Rayleigh wave, wave velocity, attenuation coefficient, dispersion characteristics