Conservation Laws for Coupled Hydro‐Mechanical Processes in Unsaturated Porous Media

Borja, Ronaldo I.; White, Joshua A.

doi:10.1002/9781118616871.ch8

Cited by 10 publications

(8 citation statements)

References 22 publications

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“…The continuum model utilized to analyze the slope satisfies balance of mass and balance of linear momentum for solid, water, and air 4, 7. For the unsaturated zone, we calculate the effective stress from the Bishop stress 8 but with the Bishop parameter replaced by the degree of saturation.…”

Section: Problem Definition and Methods Of Analysismentioning

confidence: 99%

“…Relevant triggering mechanisms are complex and include reduction of capillary pressure, surface and subsurface fluid flow, irregular topography, and local drainage boundary conditions 1, 2. Very recently, a three‐dimensional physics‐based continuum model has been proposed that captures the coupled solid deformation–fluid flow processes in variably saturated slopes 3, 4. The model is based on a mixed finite element formulation relating the solid displacement and pore pressure degrees of freedom, and realistically quantifies stresses and pore pressures responsible for triggering slope failure.…”

Section: Introductionmentioning

confidence: 99%

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Factor of safety in a partially saturated slope inferred from hydro‐mechanical continuum modeling

Borja¹,

White²,

Liu³

et al. 2011

Num Anal Meth Geomechanics

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SUMMARYRainfall weakens an earth slope and triggers mass movement. Relevant triggering mechanisms are complex and include reduction of capillary pressure due to increased saturation and frictional drag on the sediment induced by fluid flow. Physics-based continuum models utilizing modern computational tools are useful for understanding the mechanisms of deformation in partially saturated slopes; however, they do not provide a scalar indicator called 'factor of safety' that measures the potential of a given slope for mass movement. In the present work, we employ sequential calculations consisting of a physics-based finite element model that couples solid deformation with fluid flow to quantify the stress and deformation fields in a steep hillside slope subjected to rainfall infiltration. This is followed by a limit-equilibrium calculation based on the method of slices that evaluates the desired factor of safety. The field condition investigated is similar to the steep experimental catchment CB1 near Coos Bay, Oregon, which failed as a large debris flow from heavy rainfall.

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Section: Problem Definition and Methods Of Analysismentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Factor of safety in a partially saturated slope inferred from hydro‐mechanical continuum modeling

Borja¹,

White²,

Liu³

et al. 2011

Num Anal Meth Geomechanics

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“…All computations were conducted by using Geocentric, a massively parallel finite-element code for geomechanics that is built on the deal.II finite-element library (Bangerth et al 2007(Bangerth et al , 2013, p4est mesh handling library (Burstedde et al 2011), and the Trilinos project (Heroux and Willenbring 2012). The implementation of this code has been verified by checking to see that, when either one of the two pore fractions is reduced to zero, the results of double-porosity simulations are identical to the results of single-porosity simulations (Borja 2004;Borja and White 2010a). It was confirmed firsthand that the problems at hand are not subject to the inf-sup stability condition because compressible air is present throughout the simulations.…”

Section: Numerical Examplesmentioning

confidence: 99%

Hydromechanical Modeling of Unsaturated Flow in Double Porosity Media

2016

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Geomaterials with aggregated structure or containing fissures often exhibit a bimodal pore size distribution that can be viewed as two coexisting pore regions of different scales. The double-porosity concept enables continuum modeling of such materials by considering two interacting pore scales satisfying relevant conservation laws. This paper develops a thermodynamically consistent framework for hydromechanical modeling of unsaturated flow in double-porosity media. With an explicit treatment of the two pore scales, conservation laws are formulated incorporating an effective stress tensor that is energy-conjugate to the rate of deformation tensor of the solid matrix. A constitutive framework is developed on the basis of energy-conjugate pairs identified in the first law of thermodynamics, which is then incorporated into a three-field mixed finite-element formulation for double-porosity media. Numerical simulations of laboratory-and field-scale problems are presented to demonstrate the impact of double porosity on the resulting hydromechanical responses.

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“…Assuming a barotropic pore fluid as discussed in [17,53,106], a relation among the material density q FR , the pore-fluid pressure p F and the fluid compressibility…”

Section: Governing Balance Relationsmentioning

confidence: 99%

Experimental study and numerical modeling of the thermo-hydro-mechanical processes in soil freezing with different frost penetration directions

et al. 2021

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This research work presents an experimental and numerical study of the coupled thermo-hydro-mechanical (THM) processes that occur during soil freezing. With focusing on the artificial ground freezing (AGF) technology, a new testing device is built, which considers a variety of AGF-related boundary conditions and different freezing directions. In the conducted experiments, a distinction is made between two thermal states: (1) The thermal transient state, which is associated with ice penetration, small deformations, and insignificant water suction. (2) The thermal (quasi-) steady state, which has a much longer duration and is associated with significant ice lens formation due to water suction. In the numerical modeling, a special focus is laid on the processes that occur during the thermal transient state. Besides, a demonstration of the micro-cryo-suction mechanism and its realization in the continuum model through a phenomenological retention-curve-like formulation is presented. This allows modeling the ice lens formation and the stiffness degradation observed in the experiments. Assuming a fully saturated soil as a biphasic porous material, a phase-change THM approach is applied in the numerical modeling. The governing equations are based on the continuum mechanical theory of porous media (TPM) extended by the phase-field modeling (PFM) approach. The model proceeds from a small-strain assumption, whereas the pore fluid can be found in liquid water or solid ice state with a unified kinematics treatment of both states. Comparisons with the experimental data demonstrate the ability and usefulness of the considered model in describing the freezing of saturated soils.

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Conservation Laws for Coupled Hydro‐Mechanical Processes in Unsaturated Porous Media

Cited by 10 publications

References 22 publications

Factor of safety in a partially saturated slope inferred from hydro‐mechanical continuum modeling

Factor of safety in a partially saturated slope inferred from hydro‐mechanical continuum modeling

Hydromechanical Modeling of Unsaturated Flow in Double Porosity Media

Experimental study and numerical modeling of the thermo-hydro-mechanical processes in soil freezing with different frost penetration directions

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