InterPore2023

Chemo-Hydro-Mechanical variational phase-field fracture model in cementitious systems

24 May 2023, 12:30

15m

Oral Presentation (MS07) Mathematical and numerical methods for multi-scale multi-physics, nonlinear coupled processes MS07

Speaker

Dr Mostafa Mollaali (Helmholtz Centre for Environmental Research–UFZ, Leipzig, Germany)

Description

We present a fully coupled chemo-hydro-mechanical variational phase field model for simulating fracture initiation and propagation, including chemical reactions in cementitious systems. In a staggered approach, we coupled three subprocesses: (i) fluid flow in porous media, (ii) reactive transport, and (iii) mechanical deformation of fractured porous media using the variational phase field.

We use the geochemical package PHREEQC [1] coupled in an operator-splitting approach with a finite element transport solver to calculate chemical reactions in thermodynamic equilibrium (dissolution or precipitation) while taking into account changes in porosity. We couple mechanical deformation and fluid flow using the fixed-stress splitting approach. For chemical damage, we introduce a variable to a constitutive relation that represents a degree of chemical damage ranging from zero (intact) to one (damaged material). The chemical damage variable represents changes in porosity caused by chemical reactions independently from the phase field variable that represents the mechanical damage [2]. Additionally, as effective diffusion and hydraulic conductivity increase in the presence of fracture and changes in porosity, phase field variable, and chemical damage should impact the hydraulic conductivity [3] and the diffusion coefficient [2, 4, 5].

We conducted different benchmarks to demonstrate the model's capabilities and properties to capture the fracture initiation and propagation due to chemical reactions. The proposed model was implemented in the open-source finite element framework OpenGeoSys [6, 7]. The research work has been conducted in the frame of the EURAD project (in particular in the WP MAGIC).

References

[1] Parkhurst, David L., and C. A. J. Appelo. "Description of input and examples for PHREEQC version 3—a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations." US geological survey techniques and methods 6, no. A43 (2013): 497.

[2] Gerard, Bruno, Gilles Pijaudier-Cabot, and Christian Laborderie. "Coupled diffusion-damage modelling and the implications on failure due to strain localisation." International Journal of Solids and Structures 35, no. 31-32 (1998): 4107-4120.

[3] Carman, Philip Crosbie. "Flow of gases through porous media." (1956).

[4] Wu, Jian-Ying, and Wan-Xin Chen. "On the phase-field modeling of fully coupled chemo-mechanical deterioration and fracture in calcium leached cementitious solids." International Journal of Solids and Structures 238 (2022): 111380.

[5] Schuler, Louis, Anastasia G. Ilgen, and Pania Newell. "Chemo-mechanical phase-field modeling of dissolution-assisted fracture." Computer Methods in Applied Mechanics and Engineering 362 (2020): 112838.

[6] Bilke, Lars, Bernd Flemisch, Thomas Kalbacher, Olaf Kolditz, Rainer Helmig, and Thomas Nagel. "Development of open-source porous media simulators: principles and experiences." Transport in porous media 130, no. 1 (2019): 337-361.

[7] Lu, R., Nagel, T., Poonoosamy, J., Naumov, D., Fischer, T., Montoya, V., Kolditz, O., Shao, H., (2022): A new operator-splitting finite element scheme for reactive transport modeling in saturated porous media. Comput. Geosci. 163, art. 105106