Dynamic response of saturated porous elastic foundation under porosity anisotropy

Natural soils usually exhibit some anisotropic characteristics due to different deposition conditions and stress states. This study investigated the effects of coupled thermo-hydro-mechanical dynamics on an anisotropy of porosity, fully saturated, and poroelastic half-space subgrade whose surface is subjected to either thermal load or mechanical load in the direction of increasing the depth of the foundation and the direction of the wave propagation. Based on the Lord- Shulman generalized thermoelastic theory and the basic assumption of anisotropy of porosity, the coupled thermo-hydromechanical dynamic model for the porosity anisotropy saturated porous elastic foundation is established. The general relationships among non-dimensional vertical displacement, excess pore water pressure, vertical stress, and temperature distribution deduce by using normal mode analysis and depict them graphically. Normal mode analysis is a method using weighted residuals to derive analytical solutions and can thus solve partial differential equations more quickly compared to other methods. When the anisotropic parameter of porosity equals one the dynamic model of this anisotropic foundation can be reduced to a foundation model consistent with the coupled thermo-hydro-mechanical dynamic model, thus verifying the accuracy of the foundation model. The effects of anisotropic parameters of porosity on different physical variables are analyzed emphatically. The results show that the different anisotropic porosity coefficient parameters has a certain influence on all physical variables. The anisotropic porosity has a significant effect on the non-dimensional excess pore water pressure and the vertical stress when the upper surface of the foundation under thermal load, while has obviously effect on the excess pore water and temperature under mechanical load. As a whole, whatever the load is on the surface of the foundation, the peak of the curve decreases gradually and the location of the peak moves closer to the surface in the direction of increasing along the foundation depth as the increase of anisotropy parameters. © 2020, Chinese Journal of Theoretical and Applied Mechanics Press. All right reserved.