A coupled discrete approach to simulate moisture effects on damage processes in porous materials

This contribution presents the capabilities of a combined approach for describing both unsaturated moisture transport and fracture development in quasi-brittle porous materials. The fracture process is modelled by the partition-of-unity (PU) crack model, where cracks are implemented as displacement discontinuities. The moisture transport in the fractured material is modelled using a mixed continuum-discrete approach: transport in the crack is described by a moving front model while transport in the matrix is described by a continuum finite element model. The coupling between mechanical and transport phenomena is described by a poromechanical model based on the effective elastic stress concept. The coupled model allows the analysis of moisture effects on discrete damage processes in porous materials and vice versa. The capabilities of the method and the effects of moisture on dimensional stability, mechanical response, and cracking behaviour are illustrated with different examples of combined mechanical and moisture loading during three point bending tests on a fictitious sandstone.