A Practical Approach to Assess Combined Levee Erosion, Seepage, and Slope Stability Failure Modes

Brian A Hubel,Marc Goodhue,Landris T Lee,Joseph V Letter, Jr

doi:10.1061/41147(392)26

Abstract

Probability of unsatisfactory performance (system response) curves were developed for seepage, slope stability, and erosion potential failure modes during a flood reduction feasibility study. The erosion-induced breaching failure mode included water-side storm surge and wave runup with or without concurrent land-side overtopping. Response curves were developed for landside and waterside slope stability and landside seepage failure modes for various hydrostatic water loads. This paper illustrates an approach for evaluating the overall system response considering levee seepage, stability, and erosion response under various hydrodynamic loading and geomorphological uncertainties.

Highlights

Probabilistic methods to evaluate the geotechnical perfonnance of earthen levees are required to better understand economic and life-safety risks of earthen levee structures for engineers, managers, planners, and the general public
The overall perfonnance of an earthen levee system is highly sensitive to the geotechnical perfonnance of the levee
USACE guidance for project feasibility studies requires that existing systems be holistically evaluated using probabilistic methods to estimate annual damages over a standard project life cycle (USACE 2006)

Summary

Introduction

Probabilistic methods to evaluate the geotechnical perfonnance of earthen levees are required to better understand economic and life-safety risks of earthen levee structures for engineers, managers, planners, and the general public. A practical approach to define the geotechnical inputs of levee perfonnance (erosion, stability, and seepage) is presented in the sections below. The limit state is defined as a critical seepage gradient, for stability it is defined as a slope stability slip surface that extends half way through the levee crest having a factor of safety less than one, and for erosion Pu was defined as the probability of a levee breach occurrence.

Results

Conclusion