An elasto-plastic model for non-isothermal analysis of flow and deformation in unsaturated porous media: formulation

114

SUMMARYThis paper introduces an unconventional constitutive model for soils, which deals with a unified thermomechanical modelling for unsaturated soils. The relevant temperature and suction effects are studied in light of elasto-plasticity. A generalized effective stress framework is adopted, which includes a number of intrinsic thermo-hydro-mechanical connections, to represent the stress state in the soil. Two coupled constitutive aspects are used to fully describe the non-isothermal behaviour. The mechanical constitutive part is built on the concepts of bounding surface theory and multi-mechanism plasticity, whereas water retention characteristics are described using elasto-plasticity to reproduce the hysteretic response and the effect of temperature and dry density on retention properties. The theoretical formulation is supported by comparisons with experimental results on two compacted clays.

Section: Previous Contributions To the Constitutive Modelling Under Nmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

ACMEG‐TS: A constitutive model for unsaturated soils under non‐isothermal conditions

Baudin

Laloui

2008

114

“…This numerical model was developed based on poroelastic governing equations for groundwater flow in deformable, variably saturated porous media and the Galerkin finite element method [12]. Flow and deformation in unsaturated porous media were also considered using an elasto-plastic model for unsaturated soils [13].…”

Section: Introductionmentioning

confidence: 99%

Analytical solution to 1D coupled water infiltration and deformation in unsaturated soils

Zhang

2008

SUMMARYAn analytical solution to 1D coupled water infiltration and deformation is derived using a Fourier integral transform. Exponential functional forms are used to represent the hydraulic conductivity-pore-water pressure relationship and the soil-water characteristic curve. Fredlund's incremental-linear constitutive model for unsaturated soils is adopted. The analytical solution considers arbitrary initial pore-water pressure distributions and flux and pressure boundary conditions. The corresponding analytical solutions to coupled steady-state problems are also obtained. The analytical solutions demonstrate that the coupling of seepage and deformation plays an important role in water infiltration in unsaturated soils. In the early stages of infiltration, the difference between uncoupled and coupled conditions becomes marked over time, and in late stages, the difference caused by the coupling effects diminishes toward the steady state. The difference between the uncoupled and coupled conditions increases with decreasing desaturation coefficient ( ). Pore-water pressure or deformation changes caused by the coupling effects are mainly controlled by the degree of soil volume change due to a change in soil suction (H ). The smaller the absolute value of H , the greater the effect of coupling on the infiltration and deformation. The ratio of rainfall intensity to saturated permeability (q/k s ) also has a strong influence on the coupled seepage and deformation.

“…Incremental solid skeleton equilibrium can be described in a manner similar to Khalili and Loret [15]:…”

Section: Equilibriummentioning

confidence: 99%

“…In this investigation, vapor is considered a separate phase, hence it requires its own continuity equation [15]:…”

Section: Vapor Transportmentioning

confidence: 99%

A discretized analytical solution for fully coupled non‐linear simulation of heat and mass transfer in poroelastic unsaturated media

Malekzadeh

Pak

2009

SUMMARYMathematical simulation of non-isothermal multiphase flow in deformable unsaturated porous media is a complicated issue because of the need to employ multiple partial differential equations, the need to take into account mass and energy transfer between phases and because of the non-linear nature of the governing partial differential equations. In this paper, an analytical solution for analyzing a fully coupled problem is presented for the one-dimensional case where the coefficients of the system of equations are assumed to be constant for the entire domain. A major issue is the non-linearity of the governing equations, which is not considered in the analytical solution. In order to introduce the non-linearity of the equations, an iterative discretized procedure is used. The domain of the problem is divided into identical time-space elements that cover the time-space domain. A separate system of equations is defined for each element in the local coordinate system, the initial and boundary conditions for each element are obtained from the adjacent elements and the coefficients of the system of equations are considered to be constant in each step. There are seven governing differential equations that should be solved simultaneously: the equilibrium of the solid skeleton, mass conservation of fluids (water, water vapor and gas) and energy conservation of phases (solid, liquid and gas). The water vapor is not in equilibrium with water and different phases do not have the same temperature. The governing equations that have been solved seem to be the most comprehensive in this field. Three examples are presented for analyzing heat and mass transfer in a semi-infinite column of unsaturated soil.