An Investigation of the Effect of Seepage on the Stability of Sheet Pile Supported I-Wall in New Orleans, Louisiana

After the city of New Orleans, Louisiana was hit by Hurricane Katrina, an extensive investigation of the performance of the floodwalls in the New Orleans area has been undertaken by the U.S. Army Corps of Engineers (USACE) and others. Due to the unsatisfactory performance of the I-walls during the hurricane, the effect of gap formation between the cantilevered I-wall-sheet pile system and the levee embankment soil has drawn significant attention in the engineering community. The recent efforts to investigate this issue have been restricted to the study of stability of the I-wall with cohesive backfill behind the I-wall. However, it is important to note that when the sheet pile penetrates into sand layers; seepage becomes an integral part of the gap analysis which affects the stability of the I-wall. In this work, an investigation of the effect of seepage on the stability analysis of an I-wall in New Orleans, LA is presented. The present study incorporates a finite element seepage analysis prior to conducting the stability analysis. Comparative slope stability analyses have been performed for this type of complex problem to assess the accuracy and suitability of the results.