ORALS

SESSION: GeomechanicsFriPM2-R7	Schrefler International Symposium on Geomechanics and Applications for Sustainable Development
Fri Oct, 25 2019 / Room: Athena (105/Mezz. F)
Session Chairs: Patrizia Trovalusci; Christian Hellmich; Session Monitor: TBA

16:45: [GeomechanicsFriPM211] Keynote
A General Framework for the Numerical Modeling of Concrete Structures Behavior
Francesco Pesavento¹ ; Dariusz Gawin² ; Giuseppe Sciumè³ ; Marcin Koniorczyk² ; ¹University of Padova, Padova, Italy; ²Lodz University of Technology, Lodz, Poland; ³Université de Bordeaux, Bordeaux, France;
Paper Id: 222 [Abstract]

The prediction of the behavior of cementitious materials and concrete structures under severe conditions and/or for long time spans is of paramount importance in civil, environmental and nuclear engineering. Often, commercial tools do not provide a sufficiently accurate response, so it is necessary to use more sophisticated approaches. In this work, a general framework for the simulation of the non-linear behavior of concrete is shown and described. It is based on the mechanics of multiphase porous media. The mathematical model is developed by writing the relevant balance equations for the constituents at the pore scale, i.e. the local form of governing equations formulated at micro-scale, and by upscaling these equations to the macroscopic scale, taking into account thermodynamic constraints according to the so-called TCAT (Thermodynamics Constrained Averaging Theory) which assures that all the thermodynamics are properly up scaled from the micro to the macro level. Thanks to this approach, all the relevant quantities involved are thermodynamically correct, no unwanted dissipations are generated, and both the bulk phases and interfaces are taken into account. This procedure does not exclude, however, the use of a numerical multiscale approach in the formulation of the material properties. The numerical solution is obtained directly at the macro level by discretizing the governing equations in their final form. The resulting model can be usefully applied to several practical cases: evaluation of the concrete's performance at early stages of maturing massive structures [1-3], structural repair works [2,3], exposure of concrete to high temperatures, e.g. during fire [4,5], cementitious materials subject to freezing/thawing cycles [6], etc. In this work, the general model focuses on the specific situations described above and several examples are shown.

References:
[1] D. Gawin, F. Pesavento, B.A. Schrefler, Modelling creep and shrinkage of concrete by means of effective stress, Materials & Structures 40 (2007) 579-591.
[2] G. Sciume, F. Benboudjema, C. De Sa, F. Pesavento, Y. Berthaud, B.A. Schrefler, A multiphysics model for concrete at early age applied to repairs problems, Engineering structures 57 (2013) 374-387.
[3] F. Pesavento, B.A. Schrefler, G. Sciumè, Multiphase Flow in Deforming Porous Media: A Review. Archives of Computational Methods in Engineering 24 (2017) 423-448.
[4] D. Gawin. F. Pesavento, B.A. Schrefler , Modelling of hygro-thermal behaviour of concrete at high temperature with thermo-chemical and mechanical material degradation, Comput. Methods Appl. Mech. Engrg. 192(13-14) (2003) 1731-1771.
[5] D. Gawin, F. Pesavento, B.A. Schrefler, Towards prediction of the thermal spalling risk through a multi-phase porous media model of concrete, Computer Methods in Applied Mechanics and Engineering 195 (2006) 5707-5729.
[6] D. Gawin, F. Pesavento, M. Koniorczykc, B.A. Schrefler, Non-equilibrium modeling hysteresis of water freezing - ice thawing in partially saturated porous building materials, Int. Journal of Building Physics, in print.

SESSION: GeomechanicsSatPM2-R7	Schrefler International Symposium on Geomechanics and Applications for Sustainable Development
Sat Oct, 26 2019 / Room: Athena (105/Mezz. F)
Session Chairs: Gennady Mishuris; Daniela P. Boso; Session Monitor: TBA

15:55: [GeomechanicsSatPM209] Invited
From Civil Engineering to Oncophysics: Successful and Present Challenging Applications of Multiphase Porous Media Mechanics
Giuseppe Sciumè¹ ; Stefano Dal Pont² ; ¹Université de Bordeaux, Bordeaux, France; ²Laboratoire Sols, Solides, Structures, Risques (3SR), Grenoble, France;
Paper Id: 310 [Abstract]

The mechanics of porous media is among the most fascinating and interesting branches of continuum mechanics since it can be applied to extremely broad fields of science. From the beginning of the XX century, when Karl von Terzaghi postulated the effective stress principle in soils mechanics, the theory of porous media advanced substantially, particularly thanks to the contribution of Maurice Anthony Biot. He introduced the general concept of the poroelastic medium and developed the theory of dynamic poroelasticity (now known as Biot’s theory) which is the basis of porous media mechanics. More recent developments consider averaging procedures which also include interface mechanics [1]. Porous media mechanics is ordinarily used for geomechanical problems at large, but nowadays it is also applied to model biomechanical ones. Teeth and bone decalcification, herniation of intervertebral discs and glaucoma and tumor growth are examples of clinical pathologies which can be modeled using mathematical approaches based on porous media mechanics. Two very different applications are briefly presented to highlight the flexibility of this theory. The first one is a thermo-hygro-chemo-mechanical (THCM) model for concrete. The presented approach is inspired by the theoretical framework of Gawin, Pesavento and Schrefler [2]; the reference model has been further improved for structural application by accounting for shrinkage, as well as creep and mechanical damage in a fully coupled fashion. The second one is a multiphase model of tumor growth. The tumor is modeled as a four-phase system which consists of a solid phase, an extracellular matrix, and three fluid phases. The fluid phases are the interstitial fluid, tumor cells and healthy cells, with the latter two phases modeled as adhesive fluids. Since tumor growth is strongly influenced by nutrient availability, the diffusion of oxygen coming from the nearby existing vessels is also considered. Examples of biological interest will be presented.

References:
[1] Gray, W.G. and Miller C.T., "Thermodynamically constrained averaging theory approach for modeling flow and transport phenomena in porous medium systems: 1. Motivation and overview" Advances in Water Resources 28 161–180 (2005).
[2] Gawin, D., Pesavento, F. and Schrefler B.A. "Hygro-thermo-chemo-mechanical modelling of concrete at early ages and beyond. Part I: Hydration and hygro-thermal phenomena", International Journal for Numerical Method in Engineering, 67(3), 299-331 (2006).