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Computer modelling and stability analyses of the New Orleans I-walls with and without the consideration of gap formation has drawn significant attention of the engineering community during the post Katrina period. In addition, when the sheet pile penetrates into sand layer, seepage becomes an integral part of the stability analysis. Basic guidelines have been developed for the analysis of this problem by other researchers and documented by the U.S. Army Corps of Engineers (USACE). However, the inherent complexity of the problem and uncertainties associated with the choice of analysis methods warrant for further investigation of this problem in detail so that more useful insights can be gained. In this paper, a comprehensive analysis of this complex coupled problem of seepage and stability of a typical New Orleans I-wall is presented using different limit equilibrium methods of slope stability analysis. Useful comparisons are made between the analyses results and methodologies. The authors believe that the findings of this study will enhance the understanding of the behaviour of the I-wall sheet pile system subjected to seepage forces, when different limit equilibrium methods of analyses are invoked. [ABSTRACT FROM PUBLISHER]

Following Hurricane Katrina, the study of cantilevered sheet pile I-wall with gap or partial gap has become one of the central elements of the ongoing investigation pertaining to the re-building of hurricane protection systems in New Orleans, LA. Historically, the US Army Corps of Engineers (USACE) had mostly relied upon the Method of Planes (MOP) analysis procedure for slope stability analysis of I-wall systems. However MOP is a simplified procedure which does not satisfy total equilibrium. Nevertheless, MOP is still considered by USACE as a popular analysis tool because of its simplicity and ease of use in slope stability analysis. This paper demonstrates the applicability and suitability of MOP as a viable analysis tool for the analysis of New Orleans I-wall founded on layered cohesive backfill subjected to partial gap condition. The results of MOP analyses are compared with those of rigorous limit equilibrium method. Design recommendations regarding the choice of proper analysis tool for the I-wall partial gap analysis are made based on the findings of this investigation. Relative estimates of the design factors of safety recommended in the Hurricane and Strom Damage Risk Reduction System Design Guidelines (HSDRRSDG, 2007) are also presented. [ABSTRACT FROM PUBLISHER]