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.

Dynamic Modelling of Annular Plates of Functionally Graded Structure Resting on Elastic Heterogeneous Foundation with Two Modules

The contribution is devoted to formulate an averaged mathematical model describing the dynamic behaviour of the composite annular plates resting on elastic heterogeneous foundation with two foundation modules. The plates are made of two-phased, functionally graded — type composites. In contrast to most of the papers in which material properties vary through the plate thickness, in the presented study we have dealt with the plate and foundation in which effective properties vary in a radial direction of the plate. The formulation of the macroscopic mathematical model for the analysis of the dynamic behaviour of these plates will be based on the tolerance averaging technique (Woźniak, Michalak, Jędrysiak, [ed]). This averaging method is an alternative to known asymptotic homogenization. The general results of the contribution will be illustrated by the analysis of free vibrations of the composite plates on heterogeneous foundation. The results obtained from the tolerance model were compared with the results obtained from FEM. There were compared the first four natural frequencies. A good consistency of the results from both methods was obtained.