Mise au point d'un essai de compaction dynamique : application au béton

par Kamal Safa

Thèse de doctorat en Mécanique

Sous la direction de Gérard Gary et de Pascal Forquin.

Soutenue en 2008

à Palaiseau, Ecole polytechnique .

mots clés

• Essais oedométriques
• Pression intertitielle
• Béton
• Barres de Hopkinson
• Compactage

Pas de résumé disponible.

Titre traduit

Development of a dynamic compaction test for brittle materials : application on concrete

Résumé

The aim of the thesis is the development of an experimental test of uniaxial compression under static and dynamic loadings, to study the behavior of brittle material and especially concrete. The confinement device is constituted by a tubular steel ring, where the specimen in inserted using a specific protocol. The dynamic axial load is applied by the mean of Hopkinson bars device. A theoretical part of the work is to optimize the cell dimensions and to develop a reliable method of data utilization that takes into account the various parameters involved in during the test. Still in the theoretical framework but on another subject, the problem of an elastic cylinder submitted on its flat end to a uniform stress over a part of its section, is treated in order to determine the local displacement under the loaded area, called the “elastic punching”. This local displacement results from the difference between the diameter of the cylinder and the one of the loaded area, and intervenes during Hopkinson bars experiments where the diameter of the specimen is usually smaller than the one of the bar. The account of this additional displacement allows for obtaining the correct Young Modulus of the tested material. The behavior of micro-concrete MB50 was determined in dynamic, static, saturated and dry conditions. Static and dynamic tests conducted on dry and saturated concretes have shed light on several obscure points in the literature, including the influence of water pressure and the strain rate on the behaviour of concrete.