Variational modeling of hydromechanical fracture in saturated porous media

A micromechanics-based phase-field approach

authored by: Jacinto Ulloa, Nima Noii, Roberto Alessi, Fadi Aldakheel, Geert Degrande, Stijn François
Abstract: This paper presents a novel variational phase-field model for different fracture processes in fully saturated porous media. As a key feature, the model employs a micromechanics-based theory for the description of brittle-tensile and compressive–ductile fracture. As such, the field variables are linked to physical mechanisms at the microcrack level, with damage emerging as the consequence of microcrack growth. Similarly, plasticity emerges as a consequence of the frictional sliding of closed microcracks. In this way, the evolution of opening microcracks in tension leads to (mode I) brittle fracture, while the evolution of closed microcracks in compression/shear leads to (mode II) ductile fracture. These failure mechanisms are coupled to fluid flow, resulting in a Darcy–Biot–type hydromechanical model. Therein, in the tensile regime, plasticity naturally vanishes, while damage is driven by poroelastic energy, accounting for the pressure in fluid-filled opening microcracks. On the other hand, in the compressive/shear regime, the plastic driving force naturally follows as a Terzaghi-type effective stress in terms of the local stress field acting on the microcrack surfaces, while damage is solely driven by the frictionally blocked free energy. As another important feature, the model includes a non-associative frictional plasticity law. Nevertheless, a thermodynamically consistent variational framework is employed, for which different energetic principles are discussed. Finally, the numerical simulations show that the model captures relevant hydromechanical coupling effects in benchmark problems, including mechanically induced shear fracture and hydraulically induced tensile fracture.
Organisation(s): Institute of Continuum Mechanics
External Organisation(s): KU Leuven
California Institute of Caltech (Caltech)
University of Pisa
Swansea University
Type: Article
Journal: Computer Methods in Applied Mechanics and Engineering
Volume: 396
ISSN: 0045-7825
Publication date: 01.06.2022
Publication status: Published
Peer reviewed: Yes
ASJC Scopus subject areas: Computational Mechanics, Mechanics of Materials, Mechanical Engineering, General Physics and Astronomy, Computer Science Applications
Electronic version(s): https://doi.org/10.1016/j.cma.2022.115084 (Access: Closed)
: Details in the research portal "Research@Leibniz University"

BibTeX

@article{db7cd6052c8b47529b6a09a3cdbaf95f,
title = "Variational modeling of hydromechanical fracture in saturated porous media: A micromechanics-based phase-field approach",
abstract = "This paper presents a novel variational phase-field model for different fracture processes in fully saturated porous media. As a key feature, the model employs a micromechanics-based theory for the description of brittle-tensile and compressive–ductile fracture. As such, the field variables are linked to physical mechanisms at the microcrack level, with damage emerging as the consequence of microcrack growth. Similarly, plasticity emerges as a consequence of the frictional sliding of closed microcracks. In this way, the evolution of opening microcracks in tension leads to (mode I) brittle fracture, while the evolution of closed microcracks in compression/shear leads to (mode II) ductile fracture. These failure mechanisms are coupled to fluid flow, resulting in a Darcy–Biot–type hydromechanical model. Therein, in the tensile regime, plasticity naturally vanishes, while damage is driven by poroelastic energy, accounting for the pressure in fluid-filled opening microcracks. On the other hand, in the compressive/shear regime, the plastic driving force naturally follows as a Terzaghi-type effective stress in terms of the local stress field acting on the microcrack surfaces, while damage is solely driven by the frictionally blocked free energy. As another important feature, the model includes a non-associative frictional plasticity law. Nevertheless, a thermodynamically consistent variational framework is employed, for which different energetic principles are discussed. Finally, the numerical simulations show that the model captures relevant hydromechanical coupling effects in benchmark problems, including mechanically induced shear fracture and hydraulically induced tensile fracture.",
keywords = "Hydraulic fracture, Micromechanics, Non-associative plasticity, Phase-field models, Porous media, Variational formulation",
author = "Jacinto Ulloa and Nima Noii and Roberto Alessi and Fadi Aldakheel and Geert Degrande and Stijn Fran{\c c}ois",
note = "Funding Information: F. Aldakheel and N. Noii were funded by the Priority Program DFG-SPP 2020 (project number: 353757395). ",
year = "2022",
month = jun,
day = "1",
doi = "10.1016/j.cma.2022.115084",
language = "English",
volume = "396",
journal = "Computer Methods in Applied Mechanics and Engineering",
issn = "0045-7825",
publisher = "Elsevier",
}