Modélisation numérique et analytique de la fissuration de séchage des sols argileux

Abstract : This work focuses on the analysis of desiccation cracking by numerical and analytical approaches. The initiation and the propagation of cracks are investigated by using a finite element code including cohesive joints elements. Coupling between the hydraulic and the mechanical processes in the presence of discontinuities is considered. The cohesive crack’s law is applied to simulate the initiation and the propagation of cracks.Results of a laboratory experiments performed on slurry clay soil are first used to evaluate the proposed numerical modelling method. The results show that the method is able to reproduce the main trends of desiccation process. The importance of boundary conditions are also discussed. Second, an energy approach is proposed to study the initiation of cracks. The energies before and after crack initiation are estimated by both numerical and analytical solutions. The energy released by cracking is then compared to the crack energy to discuss crack initiation conditions. The analysis shows that the energy criterion is reached before the stress criterion, and this can explain unstable crack propagation at the beginning. Third, the development and the geometry of desiccation cracks are studied by numerical simulation with several cohesive joints. The numerical results show that cracking occurs sequentially to form different cracks families with a dichotomy process (the subsequent cracks appear at the middle of two existing neighboring ones). The cracks in each family appear simultaneously and reach an identical ultimate depth. From the numerical results and additional analytical analysis, empirical correlations are proposed to predict the spacing and crack depth. Finally, some preliminary studies are performed showing that the proposed numerical method can be used to predict the desiccation crack phenomena observed on geotechnical earth structures
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Thi Dong Vo. Modélisation numérique et analytique de la fissuration de séchage des sols argileux. Génie civil. Université Paris-Est, 2017. Français. ⟨NNT : 2017PESC1214⟩. ⟨tel-01680866⟩

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