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Influence de la sollicitations hydriques sur le comportement mécanique du pisé : comportement au jeune âge

Abstract : Rammed earth construction provides an efficient alternative construction material to limit energy consumption and CO2 emission. It possesses various characteristics of sustainable material, but its mechanical behavior is sensitive to humidity variations, which is a real difficulty for developing this construction technique. Thus, this study concerns the coupled hydro-mechanical behavior of rammed earth. This study is carried out using an experimental and numerical approach at both material and structural scales.At the material scale, compression and shear testing were done at different suction conditions. The samples used were compacted using a technique of static double compaction. The results showed that the mechanical parameters improved with the suction state of rammed earth. Non-linearity in the failure envelope was observed over all the suction range, and thus a modified failure criterion was proposed. The intrinsic shear parameters were determined from saturated triaxial tests. From these tests, the expression of generalized effective stress for unsaturated soils was determined.At the structural scale, the hydro-mechanical behavior of rammed earth columns was studied at non-uniform suction conditions. The columns were subjected to 1D natural convection drying, where the boundary conditions are representative of a real rammed earth wall. The drying phase kinetics were studied. The compressive testing of the columns was studied after the natural convection drying. The result showed that the strength and stiffness of the columns increased significantly within the first two weeks of drying. In addition to this, the consistency of the material changed from plastic to brittle with the increase in suction.Coupled THM simulations of the drying phase and the compression testing were performed on the rammed earth columns using the finite element code called CODE_BRIGHT. The drying simulations were carried out using more realistic atmospheric boundary conditions. A good fitting with the experimental results was obtained for drying. For the compression simulations, a linear elastic-perfectly plastic mechanical constitutive model was used. The expression of generalized effective stress was introduced in the shear strength expression. The compressive strength obtained from the simulation was compared with the experimental results. A sensitivity analysis for the effective stress parameter on the compression strength was done.Finally, a numerical case study was done to determine the drying period required for the walls to gain sufficient strength for subsequent floor construction. Two different configurations of walls were carried out at warm and cold environmental conditions while taking into account the failure criteria from the practical guide for rammed earth.
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Submitted on : Monday, March 7, 2022 - 5:20:09 PM
Last modification on : Saturday, April 23, 2022 - 3:23:54 AM
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  • HAL Id : tel-03600699, version 1

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Parul Chauhan. Influence de la sollicitations hydriques sur le comportement mécanique du pisé : comportement au jeune âge. Mechanics of materials [physics.class-ph]. Université Savoie Mont Blanc, 2021. English. ⟨NNT : 2021CHAMA007⟩. ⟨tel-03600699⟩

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