scope:

Relief wells are commonly used to reduce the pore water pressure on the river-side of levees which will eventually reduce the risk of levees and embankments failure. Two-dimensional slope stability analyses, which are commonly used, tend to smear the three-dimensional relief well water influence. Two-dimensional (2D) analyses assume that relief wells have infinite length normal to the 2D plane of the model. Three-dimensional (3D) analysis more accurately captures the seepage flow around the relief wells and considers the spacing effects of these wells on the overall groundwater analysis. This study considers a full 2D and 3D steady state finite element seepage analyses of a typical levee with different relief well setups. The pore water pressure distributions of these cases were used for 2D and 3D limit equilibrium analyses to find the slope factor of safety and probability of failure. A full comparison of the effect of relief wells is presented for the 2D and 3D models for cases with and without relief wells.