Based on the wave propagation equation in unsaturated soils

four kinds of body waves i.e. one is S wave

and other three are P waves

P1 wave

P2 wave and P3 wave

according to the wave velocity are found in unsaturated soils through theoretic deduction. Analytic expressions for wave velocity and attenuation are proposed. Numerical analysis about the relation between the wave velocity

attenuation and the void ratio and Lame constants are carried out. The results show that with the increasing of void ratio

the velocity of P1 wave and S wave become enhance; and the attenuation of three kinds of P waves becomes great

especially for P3 wave. Almost the velocity of P1

P3 and S don’t change with the changes of Lame constant

and the velocity of P2 wave become a little faster with the increasing of Lame constant Almost the attenuation of P2 wave and S wave don’t change with the Lame constant . The attenuation of P1 wave and P3 wave become smaller with the increasing of Lame constant Almost the velocity of three kinds of P waves don’t change with the variation of Lame constant

but the velocity of S wave becomes faster with the increasing of Lame constant . Almost the attenuation of P2 wave and S wave don’t change with the variation of the Lame constant . The attenuation of P1 wave and P3 wave decreases with the increasing of Lame constant

especially for P3 wave.