Development and application of new constitutive models to simulate the hydraulic-mechanical behaviour of unsaturated swelling clay

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dc.contributor.supervisor Blatz, James (Civil Engineering) en
dc.contributor.author Priyanto Putro, Deni G.
dc.date.accessioned 2007-09-14T17:44:23Z
dc.date.available 2007-09-14T17:44:23Z
dc.date.issued 2007-09-14T17:44:23Z
dc.identifier.uri http://hdl.handle.net/1993/2830
dc.description.abstract Unsaturated swelling clays are used in engineered barriers for waste disposal facilities due to their self-sealing ability and low hydraulic conductivity. The characterization of unsaturated clay behaviour is required for design of these barriers. In recent years, several small-scale laboratory and full-scale field tests have been conducted to characterize the mechanical and hydraulic behaviour of the unsaturated swelling clay. This focus of the present study is towards the development of constitutive models to simulate hydraulic and mechanical behaviour of precompacted unsaturated swelling clay, called the bentonite-sand buffer (BSB) material. Development, calibration, implementation, and application of the proposed constitutive models form the scope of the study. The results of laboratory triaxial tests with controlled suction and suction measurements are used to calibrate the constitutive models presented. An algorithm, called the PEM (Parameter Evaluation Method), which is useful to estimate constitutive model parameters and evaluate the performance of constitutive models is proposed. This algorithm has been used to estimate the parameters of two elasto-plastic constitutive models (i.e., the BBM (Alonso et al. 1990) and the BGM (Blatz and Graham 2003)) based on the laboratory tests results on the BSB material. New 3-dimensional porosity-dependent permeability model (kwn) and water retention surface (WRS) are developed in this study. The mathematical formulations of these models using parameters calibrated with laboratory tests conducted on the BSB material are provided. Implementation algorithms of the BBM, the BGM, the kwn, and the WRS in 2-phase flow hydraulic-mechanical (H-M) analysis using a 2D-finite difference method are also provided . Three combinations of hydraulic and mechanical constitutive models (linear elastic model, BGM, vanGenuchten (1980) and kwn models) are used to simulate small-scale infiltration processes in the BSB material. Two types of tests, constant volume (CV) and constant mean stress (CMS) tests are simulated using 2D-finite difference H-M analysis. The full-scale isothermal test (ITT) of AECL is modelled using 3 combinations of H-M constitutive models. The ITT experiment comprises of buffer, rock, and concrete materials. The selected combinations of H-M constitutive models are used in three types of analyses: buffer-only (BO); buffer-rock with 20x30m domain (BR); and time-dependent boundary conditions (BCt). The results of the study show that the applications of the elasto-plastic mechanical constitutive models and porosity-dependent permeability (kwn) model are improvements over existing constitutive models to model this class of problem. The rock properties and applied boundary conditions are significant in modelling the ITT experiment. The application of the time-dependent boundary condition can reduce the uncertainty of the rock properties and boundary conditions within the rock, so that it improves the model ability to simulate the hydraulic-mechanical behaviour of unsaturated swelling clay. en
dc.format.extent 31929265 bytes
dc.format.mimetype application/pdf
dc.language.iso en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject constitutive model en
dc.subject unsaturated en
dc.subject clay en
dc.subject simulation en
dc.title Development and application of new constitutive models to simulate the hydraulic-mechanical behaviour of unsaturated swelling clay en
dc.type info:eu-repo/semantics/doctoralThesis
dc.degree.discipline Civil Engineering en
dc.contributor.examiningcommittee Stimpson, Brian (Civil Engineering); Chandler, Neil (Civil Engineering); Bartley, Johnatan (Mechanical Engineering); Vanapalli, Sai (University of Ottawa) en
dc.degree.level Doctor of Philosophy (Ph.D.) en
dc.description.note October 2007 en

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