Adaptive simulation of the coupled chemo-mechanical concrete degradation

The concrete blocks containing nuclear waste are degraded by the combined action of chemical attack (leaching) and mechanical damage. The simulation of this phenomenon is essential to predict the long life behavior of these concrete containers. This degradation phenomenon results in a transient, highly nonlinear coupled problem. The simulation of coupled chemo-mechanical phenomena requires adaptivity to properly describe the multi-scale character of the solution using a reduced amount of degrees of freedom. The practical implementation of this kind of models uses often the method of lines. Using this approach the discretization of the space and the time are nearly orthogonal. While the time stepping is conceived as a technique to numerically solve an ODE, the meshing of the spatial domain is used to approximate the steady part of the equation, which is elliptic. Thus, in this work, the selected error control techniques are different for space and time. The error associated with the time stepping is estimated and controlled using a standard approach for ODEs. The time error is controlled such that it is at least one order of magnitude less than the space error. The error associated with the mesh size is estimated using a residual type error estimator. The prescribed tolerance for the space error is one order of magnitude larger than the time tolerance and, consequently, the effect of the time integration in the space error may be considered negligible. Refs. 3 (author)