Traduction technique français anglais de la thèse de doctorat de Bassels Seif El Dine intitulée « Etude du comportement mécanique de sols grossiers à matrice »
Université : École des ponts ParisTech (École nationale des ponts et chaussées)
Copyright : Bassels Seif El Dine 2010
French english scientific translation series : Phd thesis entitled : « A study of the mechanical behavior of matrix coarse-grained soils ».
Phd Student : Bassels Seif El Dine
University : École des ponts ParisTech (former : École nationale des ponts et chaussées), FRANCE
Coarse-grained soils occur abundantly in nature, especially in mountainous regions. These soils are composed of a mixture of different types of elements with variable sizes, ranging from a few fractions of a micron (clay particles) to several tens of centimeters (for example, blocs of rock in the glacial moraines). Matrix coarse-grained soils are a special case of coarse-grained soils composed of inclusions (macro-elements) of variable sizes within predominantly sandy, silty, or clayey fine-grained matrices. The presence of large elements in these matrix coarse-grained soils poses the challenging problem of their mechanical characterization. Particularly, to this day there is no reliable tool enabling us to take into account in a truly rational way these soil types in real-life projects, in order to compute and dimension works (deformability parameters, failure criteria, etc. …).
The objective of our research is to contribute to enriching our knowledge of the mechanical behavior of matrix coarse-grained soils, and propose a rational procedure for the characterization of their mechanical behavior. In order to realize this objective, it is important to understand the effect of large elements in these soils. For this, we will work on benchmark sandy matrix coarse-grained soils so we can better understand the effect of inclusions on the mechanical behavior of the mixture.
Our research is a continuation of the research conducted within the framework of Pedro’s thesis . It is also part of the CEDRE Franco-Lebanese bilateral cooperation project between ENPC-CERMES and the Lebanese University’s faculty of engineering, Beirut. This thesis is divided into 5 chapters:
The first chapter presents the bibliographic study. We emphasize in situ and laboratory characterization tests of coarse-grained soils as well as reconstitution methodologies to determine the mechanical behavior with the help of laboratory devices of classical size. We also provide a few results obtained on the impacts of fundamental parameters on the mechanical behavior of the coarse-grained soils.
The second chapter presents the experimental laboratory devices and the experimental procedure used in our research. The first device is the large-diameter triaxial device developed at CERMES, which enables the testing of soil test tubes with a diameter of 300 mm and a height of 600 mm. The second device is the large direct shear box, developed at the Lebanese University and used for testing large parallelepiped soil test tubes with a width of 300mm and a height of 180 mm.
The third chapter is devoted to characterizing the benchmark coarse-grained soil using the large-diameter triaxial device (Ø 300 mm). In that chapter, we investigates the effect of the fundamental parameters (volume fraction, size and granulometric spread of the inclusions and soil matrix density) as well as the effect of the initial consolidation constraint on the observed mechanical behavior.
The fourth chapter deals with the characterization of our benchmark coarse-grained soil using the large direct shear box. In that chapter, we also present the study the effect of fundamental parameters (volume fraction, size and granulometric spread of inclusions), followed by a comparative study of the results obtained from these two devices to evaluate them relative to each other.
The fifth chapter presents the proposed methodology that enables the estimation of the mechanical behavior of matrix coarse-grained soils at ground failure with the help of classical size laboratory devices, followed by an application of this method to naturally occurring coarse-grained soils.