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A TWO-SCALE COMPUTATIONAL FRAMEWORK FOR HYDRO-MECHANICAL COUPLINGS IN QUASI-BRITTLE HETEROGENEOUS POROUS MEDIA INCLUDING TRANSIENT AND DAMAGING EFFECTS

par Mercatoris, Benoît ;Sluys, Lambertus J.;Massart, Thierry,Jacques
Référence 11th World Congress on Computational Mechanics (WCCM XI)(20-25 July 2014: Barcelona)
Publication Publié, 2014-07-25

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Résumé :

A coupled two-scale framework based on computational homogenisation is proposed for problems combining damage processes and moisture flow in saturated heterogeneous porous geomaterials such as masonry, concrete, soil or rock. Due to their texture and the quasi-brittle nature of their constituents, complex hydro-mechanical behaviours such as damage-induced permeability and anisotropic properties may occur. This results in preferential directions for cracking and moisture transport. The characterisation of hydro-mechanical behaviour of heterogeneous porous geomaterials by means of macro-scopic closed-form constitutive laws is complex. As a complementary approach, multi-scale computational strategies aim at solving this issue by bridging both the constituents and macroscopic scales. Based on postulated constituent properties and averaging theorems, computational homogenisation allows deducing an average structural response from a representative volume element (RVE). The constituents inside the RVE may be modelled using a closed-form formulation, depending on the multi-physical phenomena to be represented. Such methods were developed for thermo-mechanical problems in [1] using astaggered approach, a fine-scale steady-state assumption and periodic constraints applied at the boundary of the RVE. A variational homogenisation procedure, taking into account fine-scale transient phenomena and based on (strong) uniform boundary conditions applied to the fine-scale RVE, was recently proposed for consolidation problems in [2]. In this contribution, a monolithic computational homogenisation procedure is proposed for the non-linear coupled hydro-mechanical behaviour of saturated heterogeneous porous media.The procedure involves the application of macroscopic strains, pressure gradients and pressure in an average sense to an RVE; and to deduce the corresponding stresses, fluxes and fluid storage, as well as the hydro-mechanical coefficients by solving a mesostructuralboundary value problem. The scale transitions are adapted to take the transient effects at the fine scale into account. The periodicity argument is addressed. A damage model including hydro-mechanical couplings is incorporated at the RVE level in order to capture damage-induced anisotropy with fracture processes and fluid flow inside cracks [3]. Using the proposed multi-scale framework and parallel computation tools, simulations are performed for heterogeneous porous materials under hydraulic and mechanical loadings.The multi-scale solutions are compared to direct numerical simulations.