PhD defense : Experimental study and modelling of the elastoplastic behaviour of unbound granular materials under large number of cyclic loadings at various initial hydric states

PhD defense: Peng JING

Team : GCE

Title : Experimental study and modelling of the elastoplastic behaviour of unbound granular materials under large number of cyclic loadings at various initial hydric states

Abstract : Granular materials are often used in low traffic pavement structures as unbound granular base and sub-base layers. In practice, low traffic pavements are subjected to variable mechanical and hydraulic loadings. Under the successive loading and unloading cycles, particles damage may accidentally occur, which leads to fine content changes and the various moisture content may cause unsaturated state changes. However, most current pavement design methods do not consider the variations above, which have a significant influence on the stiffness of the granular material layers in low traffic pavements. The objective of this context is a better understanding of hydromechanical behaviour (deformation behaviour mainly) of the unsaturated granular materials under repeated loading taking into consideration the various coupled effects: water content and fine content. A series of RLTTs are conducted with the different remolded Missillac sand samples at different water contents and fine contents to characterize the permanent and resilient deformation behaviour. Besides, the soil water retention curves (SWRCs) of Missillac sands with different fine contents are obtained by suction tests.
Then, based on the experimental results, the existing permanent and resilient deformation models are improved to accommodate to the changeable fine content and water content. In the end, the shakedown behaviour of Missillac sand is estimated with the effects of fine content and water content.

Cette thèse a été dirigée par Cyrille Chazallon et co-dirigée par M. Migault de l'INSA de Strasbourg.

The presentation will be held on Thursday, March 9th mars 2017 at 13h30 in the Amphitheater Arts & Industries at INSA Strasbourg.