Étude sur modèle physique du renforcement des sols par colonnes en « Soil-Mix » : application aux plates-formes ferroviaires

Abstract : The present work deals with the behaviour of soil-mix columns used to reinforce railway platforms in France. This research, mainly experimental, is based on a physical modelling approach. Two case studies have been conducted, the degradation of the local friction mobilized at the interface soil-column and the mechanical behaviour of the material “soil-mix” at young age under cyclic loading. Concerning the degradation of the local friction mobilized at the interface soil-column, an experimental program on a physical model has been carried out. A model of a column slice instrumented with load sensors within a mass of reconstituted silt has been developped. The main objective was to evaluate the local skin friction mobilized along the soil-mix column under monotonic and cyclic loading. The main point of interest was the evolution of skin friction under large number of cycles (100 000 cycles). The experimental program highlighted the influence of key parameters such as the cyclic displacement amplitude, the vertical stress applied to the soil sample, the loading direction. The results obtained show a good consistency with the results of the literature on steel piles in sand. In a second step, we studied the effect of cyclic loading on the behaviour of the material “soil-mix” during the first hours after the realization of the columns. This case is directly related to the railway context in which the constraint of traffic continuity is one strong request of SNCF. Tests on a simplified physical model have been carried out in order to study the mechanical behaviour of the material "soil mix" at 2h, 4h, 6h, 8h, 12h and 24 h after realization of the column and after 2000 loading cycles. It has been shown that the cyclic loading does not cause degradation of the "soil-mix" material. On the contrary, there is an increase of the unconfined compression strength, the higher as the column is loaded rapidly after its realization
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van Cuong Le. Étude sur modèle physique du renforcement des sols par colonnes en « Soil-Mix » : application aux plates-formes ferroviaires. Matériaux. Université Paris-Est, 2014. Français. ⟨NNT : 2014PEST1029⟩. ⟨tel-01124321⟩

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