3D Evaluation of Levee Cutoff Wall End-Around Underseepage for Fully-Penetrating Walls

Three-dimensional steady-state seepage analyses are performed using the finite element method to evaluate levee cutoff wall end-around underseepage for fully-penetrating walls. Results from three-dimensional analyses are evaluated to develop an understanding of underseepage flow patterns arising from end-around. An existing simplified end-around evaluation procedure used in engineering practice is compared to results from the three-dimensional analyses to assess the accuracy of the simplified method. Compared to three-dimensional analyses, the existing simplified method is found to predict higher total heads near the cutoff wall transition and lower total heads at greater distances behind the wall. A new simplified method based on the existing procedure is proposed to improve the estimates of head beneath the blanket while also remaining appropriately conservative near the cutoff wall transition. Comparison of the new method to three-dimensional analyses for a wide range of cases confirms it improves the accuracy of the existing simplified approach for levee cutoff wall end-around evaluations.