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    Hydro-mechanical modeling of cohesive crack propagation in multiphase porous media using the extended finite element method

    , Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 37, Issue 10 , July , 2013 , PP. 1247–1279 Mohammadnejad, T. (Toktam) ; Khoei, A. R. (Amir Reza) ; Sharif University of Technology
    Abstract
    In this paper, a numerical model is developed for the fully coupled hydro-mechanical analysis of deformable, progressively fracturing porous media interacting with the flow of two immiscible, compressible wetting and non-wetting pore fluids, in which the coupling between various processes is taken into account. The governing equations involving the coupled solid skeleton deformation and two-phase fluid flow in partially saturated porous media including cohesive cracks are derived within the framework of the generalized Biot theory. The fluid flow within the crack is simulated using the Darcy law in which the permeability variation with porosity because of the cracking of the solid skeleton... 

    Multiscale Modeling of Cohesive Crack Growth based on XFEM and Damage Model

    , M.Sc. Thesis Sharif University of Technology Salahi Nezhad, Mohammad (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    In this research, multi-scale modeling of mixed-mode failure mechanism of quassi-brittle materials is presented. For modeling a realistic crack growth in heterogeneious media, crack initiation criterion, crack growth orientation and the macroscopic cohesive law are derived from a microscopic sample. As a microscopic crack initiation criterion, acoustic tensor is investigated and scaled acoustic tensor has been proposed by comparison its results with maximum principal tensile stress. For crack growth direction based on micro-scale, acoustic tensor and multiscale aggregating discontinuities has been investigated and multiscale aggregating discontinuities by comparison results of these methods... 

    Dynamic Modeling of Cohesive Crack Propagation in Multiphase Porous Media Using the Extended Finite Element Method

    , Ph.D. Dissertation Sharif University of Technology Mohammadnejad, Toktam (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    In this thesis, a fully coupled numerical model is developed for the modeling of the cohesive crack propagation and hydraulic fracturing in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The solid phase displacement, the wetting phase pressure and the capillary pressure are taken as the primary variables of the three-phase formulation. The other variables are incorporated into the model via the experimentally determined functions that specify the relationship between the hydraulic... 

    XFEM Modeling of Dynamic Cohesive Crack Propagation in Saturated Porous Media

    , M.Sc. Thesis Sharif University of Technology Babazadeh, Mohsen (Author) ; Khoei, Amir Reza (Supervisor)
    Abstract
    In this thesis, a fully coupled numerical model is developed for the modeling of dynamic cohesive crack propagation and hydraulic fracture in saturated porous media using extended finite element method. Many engineering structures like concrete or soil dams and buildings foundation are built with porous materials like concrete, rock and soil. Behavior of these materials in which void among the solid particles are filled with one or more fluids are so complicated rather than single solid phase. Dynamic analysis of porous mediums containing a discontinuity has many applications in various civil engineering fields including structure, earthquake, hydraulic structures, etc. For instance... 

    3D modeling of cohesive crack growth in partially saturated porous media: A parametric study

    , Article Engineering Fracture Mechanics ; Vol. 124-125, issue , 2014 , pp. 272-286 ; ISSN: 00137944 Barani, O. R ; Khoei, A. R ; Sharif University of Technology
    Abstract
    In this paper, the 3D cohesive crack propagation is presented in partially saturated porous media. The double-nodded zero-thickness cohesive interface elements are employed to capture the mixed mode fracture behavior. In order to describe the behavior of fractured media, two balance equations are applied similar to those employed for the mixture of solid-fluid phase in semi-saturated media, including: the momentum balance of fractured media, and the balance of fluid mass within the fracture. Crack permeability is modified based on the data obtained from experimental results to consider the roughness of fracture walls effect  

    An extended finite element method for hydraulic fracture propagation in deformable porous media with the cohesive crack model

    , Article Finite Elements in Analysis and Design ; Volume 73 , 2013 , Pages 77-95 ; 0168874X (ISSN) Mohammadnejad, T ; Khoei, A. R ; Sharif University of Technology
    Abstract
    In this paper, a fully coupled numerical model is developed for the modeling of the hydraulic fracture propagation in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The fluid flow within the fracture is modeled using the Darcy law, in which the fracture permeability is assumed according to the well-known cubic law. By taking the advantage of the cohesive crack model, the nonlinear fracture processes developing along the fracture process zone are simulated. The spatial discretization... 

    Hydro-mechanical modeling of cohesive crack propagation in multiphase porous media using the extended finite element method

    , Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 37, Issue 10 , 2013 , Pages 1247-1279 ; 03639061 (ISSN) Mohammadnejad, T ; Khoei, A. R ; Sharif University of Technology
    2013
    Abstract
    SUMMARY: In this paper, a numerical model is developed for the fully coupled hydro-mechanical analysis of deformable, progressively fracturing porous media interacting with the flow of two immiscible, compressible wetting and non-wetting pore fluids, in which the coupling between various processes is taken into account. The governing equations involving the coupled solid skeleton deformation and two-phase fluid flow in partially saturated porous media including cohesive cracks are derived within the framework of the generalized Biot theory. The fluid flow within the crack is simulated using the Darcy law in which the permeability variation with porosity because of the cracking of the solid... 

    Hydro-mechanical modeling of two-phase fluid flow in deforming, partially saturated porous media with propagating cohesive cracks using the extended finite element method

    , Article Computational Plasticity XI - Fundamentals and Applications, COMPLAS XI, 7 September 2011 through 9 September 2011 ; September , 2011 , Pages 1516-1527 ; 9788489925731 (ISBN) Mohammadnejad, T ; Khoei, A. R ; Sharif University of Technology
    Abstract
    In the present paper, a fully coupled numerical model is developed for the hydromechanical analysis of deforming, progressively fracturing porous media interacting with the flow of two immiscible, compressible wetting and non-wetting pore fluids. The governing equations involving the coupled two-phase fluid flow and deformation processes in partially saturated porous media containing cohesive cracks are derived within the framework of the generalized Biot theory. The displacement of the solid phase, the pressure of the wetting phase and the capillary pressure are taken as the primary unknowns of the three-phase formulation. A softening cohesive law is employed to describe the nonlinear...