شبیه سازی مواد واکنشی در آزمون ستون و مخزن. تجزیه و تحلیل حساسیت برای یک مدل خطی توأم

This paper presents results of simulations of reactive deformable porous material studied in configurations corresponding to the two classical methods of identification of transport parameters: column and reservoir tests. In order to quantify the relative importance of input parameters of the model which influence the material behavior in response to a chemical load, the sensitivity analysis is performed. The obtained results can be useful in selection of efficient methods of identification of chemo-mechanical parameters and in particular, finding the optimum source and time period of the tests.

The class of reactive (or chemically sensitive) materials includes wide range of natural media such as clays and soft tissues and many artificial materials, mostly hydro-gels and porous polymers which are developed and applied as smart or multifunctional media. The modeling of the reactive materials should include response to mechanical and chemical leads and is associated with description of deformations, flow and transport. Mechanically driven deformations of porous materials are incorporated in the theory of consolidation. The evolution of physicochemical interactions within or between elements of solid material (particles) due to change in pore fluid chemistry is the most important cause of non-mechanical deformations of the materials. The flow and advective–diffusive transport in very low permeability materials like clay and gels are limiting cases of the more coupled transport phenomena, which include osmosis and ultrafiltration. This is due to the fact that clay and some other gels act as semi-permeable membranes. Models of consolidation coupled with transport of chemicals in reactive materials within purely macroscopic approach are based on theory of chemo-consolidation, [1] and [2] the theory of poroelasticity with chemical effects [3], or theory of mixtures [4], [5] and [6] and are related to reversible [1] and [3] or irreversible [7] deformations of solids matrix. The other approaches use the averaging techniques [5] and [8] starting from continuum or molecular level. A significant component of any modeling is identification of material parameters. This becomes a particularly non-trivial task for such complex behavior as exhibited by reactive materials for which there is essential lack of complete set of the parameters. The very important for indirect identification of the material parameters or functions are simulations of experimental tests. The simulations based on analytical or numerical solutions are useful in sensitivity analysis and then design of procedures that are efficient from the point of view of the actual estimation process. The subject of this paper is the analysis of numerical models of reactive deformable porous materials studied in configurations corresponding to the two classical methods of identification of transport parameters: column and reservoir tests. The tests which are usually used to determine transport parameters of undeformable porous materials are considered here as potential methods which incorporate chemically induced deformations and couplings resulting from interaction of mechanical and chemical loads. First, using linear chemo-mechanical models of the tests the 1D numerical simulations are developed. The solutions are applied to perform thorough sensitivity analysis concentrated on studies of influence of material parameters present in the models on observable outputs – concentration, pressure and displacement.

The experimental configurations which are usually used to determine transport parameters of undeformable porous materials were considered as potential methods of identification of parameters of chemo-mechanical model of reactive materials. First, using linear 1D model of the tests numerical simulations were developed. Then, using the simulations the sensitivity analysis was performed with respect to parameters representing chemo-mechanical and chemo-osmotic couplings. The quantities for which the sensitivities were studied were selected taking into account the possibility of their control in real tests. The results show very low sensitivity of concentration with respect to considered parameters for both configurations. The sensitivity of pressure at the impermeable boundary of the reservoir test is significant with respect to parameter d and low for b1. The settlement of the sample, irrespective of the test, in the first period is sensitive to b1 and then to d. The sensitivity plots for pore pressure and settlement with respect to d and b1 gave the evidence of existing correlation of sensitivities which should be kept in mind in inverse modeling and selection of the optimum time window for data acquisition. From the practical point of view the obtained results indicate that the column test is essentially less valuable for estimation of material parameters of coupled chemo-mechanical model than the reservoir test. The latter one offers more relatively easy measured quantities (reservoir concentration, bottom pressure and settlement of sample) and also the measured data are better data source for inverse analysis.