Coupled hydro-mechanical modeling of swelling processes of clay-sulfate rocks

Swelling of clay-sulfate rocks is a well-known phenomenon often causing threats to the success of geotechnical projects such as tunneling, road and bridge construction. The origin of clay-sulfate swelling is usually explained by physical swelling due to clay expansion combined with chemical swelling associated with the transformation of anhydrite into gypsum. In practice, predicting the swelling behavior is complex, potentially involving geological, mineralogical, chemical, hydrological and mechanical processes. Planning appropriate counter measures to the swelling problem requires a thorough understanding of the coupled processes involved. This contribution deals with the development of a hydromechanical coupled model for swelling of clay-sulfate rocks. The mathematical model is implemented into the scientific open-source framework OpenGeoSys (Kolditz et al., 2012; Bilke et al., 2019). The model results are compared to field measurements obtained from the study site Staufen, Germany.