Liquefaction Susceptibility of an Earth Dam Foundation: A Case Study 

Sidi El Barrak earth dam is a compacted earth embankment of height 28 m built in 1999 on a heterogeneous foundation with strong dominance of sandy formations. The dam foundation was subjected to several tests to predict its behavior against the liquefaction risk. Standard penetration test (SPT) results served to evaluate the liquefaction risk in an earthquake occurrence. This article, firstly, presents an interpretation of data collected from SPT tests. Determination of liquefaction risk resulted from the empirical methods proposed by Seed & Idriss, (1985) and Idriss & Boulanger, (2008). Obtained results by those methods showed that, for different earthquake magnitudes equal to 5.25, 6 and 6.75, the risk of liquefaction exists in the pure sand layer located between the ground surface and 15 m depth of the foundation of the earth dam. An UBC3D-PLM constitutive model was adopted for studying the numerical response of sand layer subjected to an earthquake of acceleration equal 0.2 g to estimate its liquefaction risk. Recorded SPT data and laboratory tests results served for the determination of geotechnical parameters of this model. From numerical predictions it revealed that the liquefaction risk is greater for an earthquake characterized by an acceleration equal 0.2g.