Modélisation de la consolidation au dégel à grandes déformations

Authors: Dumais, Simon
Advisor: Konrad, Jean-Marie
Abstract: This thesis presents the development of an engineering method for the modelling of large strain nonlinear thaw consolidation. The work presented herein follows existing thaw consolidation theories and models. The foundations of one-dimensional thaw consolidation theory are therefore used. First, a numerical model for large strain nonlinear thaw consolidation is formulated by combining the Gibson large strain consolidation theory to heat transfer equations. The two components are coupled in a modelling domain formulated in Lagrangian coordinates that adapts to the soil deformation. This results in the introduction of a second moving boundary at the soil surface to model thaw consolidation in addition to the moving boundary at the thaw front. The model uses nonlinear σʹ<sub>v</sub> – e – k<sub>v</sub> relationships to define the properties of thawed soils. A case study of the Inuvik experimental pipeline with the numerical model is presented. The case study demonstrates the use of the model for a practical problem and it is used to validate the model. The modelling results are compared to the results obtained with the small strain linear thaw consolidation theory and with the field data. The results obtained with the large strain nonlinear model for thaw settlement, the rate of thaw settlement and the excess pore pressures compare favourably with the field data. Second, a conceptual model for thaw consolidation of thawed fine-grained soils is proposed. The model is used to define the characteristics of the nonlinear σʹ<sub>v</sub> – e – k<sub>v</sub> relationships used as input for the numerical modelling of thaw consolidation. The concept of the residual stress is generalized to ice rich soils by specifying that it is the effective stress within the soil element rather than the effective stress of the bulk soil. Then, empirical relationships are formulated to determine the characteristics of the σʹ<sub>v</sub> – e – k<sub>v</sub> relationships as a function of the initial thawed void ratio and soil index properties.
Document Type: Thèse de doctorat
Issue Date: 2019
Open Access Date: 13 December 2019
Grantor: Université Laval
Collection:Thèses et mémoires

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