Transient Analysis of Instability in Saturated Sand under Undrained Triaxial Loading Condition

The present study focuses on finite element analysis (FEM) of instability in saturated sands. The numerical simulation is performed under undrained conditions on the saturated triaxial specimen prepared by the moist tamping method. The differing behaviours of the granular material under steadystate and transient analysis are explored further. The steady-state analysis does not incorporate the flow of fluid in the pores of the soil sample. Whereas, the transient analysis considers the flow of pore fluid (solid-fluid diffusion) in the materials and allows the local drainage in the materials while globally remaining undrained. This study points towards the consideration of transient analysis in the simulation of saturated sand as it significantly influences the onset of instability. To simulate the nonhomogeneous sample, the density is varied along the height of the sample. The deviation in local responses for the nodes from each other is considered to identify the onset of instability. In transient analysis, it is found that the coupling mechanism between solid-fluid phases delayed the onset of instability and reduced the level of plastic deformation in the materials as compared to steady-state analysis.