DYNAMIC RESPONSES OF GRADED NON-HOMOGENEOUS UNSATURATED SOILS UNDER A STRIP LOAD

Based on the three-phase porous media mixed theory, a graded non-homogeneous unsaturated foundation model is established and the dynamic response of graded non-homogeneous unsaturated soils subjected to a strip load is addressed. The general solutions of dynamic response for unsaturated foundation in frequency domain are derived by using the Fourier transform and Helmholtz vector decomposition. Then the calculation formula of displacement, stress, and pore pressure of graded non-homogeneous unsaturated soil is derived by combining with the reverberation-ray matrix method (RRMM), boundary conditions and general solutions of dynamic response for unsaturated foundation in frequency domain. Assuming that the continuous variation of physical and mechanical properties of unsaturated soils along the thickness-coordinate by exponential law distribution, the numerical solutions of displacement, stress, and pore pressure then obtained by using numerical inverse Fourier transformation, and the influence of soil heterogeneity on the dynamic response of unsaturated soil is discussed. The results show that the non-homogeneous of unsaturated soil has a considerable effect on the dynamic response of unsaturated soil, which significantly changes the vibration modes of vertical displacement, normal stress and pore pressure in the depth direction. The vibration frequency of pore air pressure in the depth direction increases with the increase of gradient factor, and the peak wave is constantly near the surface. The vertical displacement decreases with the increase of gradient factor, but the normal stress and pore water pressure first increase and then decrease with the increase of gradient factor, and the higher nonhomogeneity of soil is, the greater amplitude of normal stress and pore water pressure is.