Instability Analysis of Coupling Seepage and Stress Field in Unsaturated Soil

The instability of seepage and stress field coupling in unsaturated soil caused by wet process, resulted stability change in unsaturated soil.Thus,it is important to analysis the conditions of the coupling stability not in theory but in engineering. A coupled seepage and stress field model was derived from the transport laws in continuum mechanics and Darcy's law, integrated with fluid motion in porous media. Then, a linear instability analysis was performed to investigate the general conditions of which kind would trigger the non-stability of the coupling field. Finally, some variables, which have a significant effect on the onset of the instability of the unsaturated system subjected to the instability of the coupled model, were proposed in some simplified conditions.