hatem karoui

Studying the stability of slopes is of great interest since it is associated to various geotechnical applications, e.g., access embankments and landslide mitigation. This paper describes the research conducted to determine the failure load applied at the top of excavations in sandy soils during the construction of deep digs without the use of retaining systems. An experimental program was performed to measure the failure load of ten laboratory-compacted sand slope models that were constructed using different slope angle values and different locations for the applied loading, which consisted of an imposed uniform rate of vertical displacement at the top of the slope. Then, a three-dimensional (3D) numerical model of the laboratory tests was developed to simulate the observed behavior during the experiments by the Plaxis 3D code. The Mohr–Coulomb (MC) and hardening soil (HS) models were used to describe the behavior of the compacted sand. The results showed that the 3D numerical simul...

This paper studied the numerical simulation of wet deposited Phosphogypsum (PG) embankment on an existing dry one by the Plaxis and Midas GTS geotechnical codes. Following the sequences of PG embankment construction, a plane strain model permitted the simulation of the conventional wet deposit process of PG. Mohr-Coulomb constitutive model with appropriate parameters describe the behavior of Tunisian Phosphogypsum residue. The implementation of suitable numerical procedure led to predict the evolution of settlements and horizontal displacements during the construction of PG embankment. Comparison between predictions by Plaxis and Midas codes overall showed similar trends, in particular, the occurrence of maximum settlements after the construction of peripheral basins located at the crest of PG embankment, while the lowest settlement occurs under the central basin located at the axis of whole PG embankment. For each stage of PG embankment construction, the predictions showed constant settlement. The adopted stage construction scheme highlighted alternated settlement and heave movements, from which observed in situ cracks within the PG deposited PG were justified.

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...

This paper studied the numerical simulation of wet deposited Phosphogypsum (PG) embankment on an existing dry one by the Plaxis and Midas GTS geotechnical codes. Following the sequences of PG embankment construction, a plane strain model permitted the simulation of the conventional wet deposit process of PG. Mohr-Coulomb constitutive model with appropriate parameters describe the behavior of Tunisian Phosphogypsum residue. The implementation of suitable numerical procedure led to predict the evolution of settlements and horizontal displacements during the construction of PG embankment. Comparison between predictions by Plaxis and Midas codes overall showed similar trends, in particular, the occurrence of maximum settlements after the construction of peripheral basins located at the crest of PG embankment, while the lowest settlement occurs under the central basin located at the axis of whole PG embankment. For each stage of PG embankment construction, the predictions showed constant...

Sidi El Barrak is a Tunisian earth dam of height 28 m; it was built in 1999 on a heterogeneous foundation that has a strong dominance of sandy formations. This dam covers an area of 896 km2 and receives about 260 Millions cubic meters of water per year. The foundation of the Sidi El Barrak dam was treated by vibro-compaction over the first 10 meters, to improve the relative density of upper sand layer against the liquefaction risk. Monitoring the behavior of the dam was assured against the hydraulic behavior and topographic auscultation. The recorded peak settlement at the crest level since July 3rd, 2003 until August 2015 was about 18.7 cm. In order to reproduce the behavior of the dam in terms of consolidation, a plane strain numerical model of the dam and soil foundation has been proposed. The simulation of dam behavior using the Mohr–Coulomb model for the material of dike and the sandy layer and by adopting the Soft Soil Model for clay layer led to predicted settlement almost in...