Comparative evaluation of hydro-mechanical models in swelling of clay-sulfate rocks: Case study of staufen, Germany

The swelling of clay-sulfate rocks presents a substantial challenge in geotechnical engineering, with the city of Staufen in Germany being a case study, where ground deformations were triggered by water flow into the Triassic Grabfeld Formation. The underlying mechanisms include clay swelling and chemical swelling from the transformation of anhydrite to gypsum, both leading to a volume increase. This research developed two hydro-mechanical (HM) models based on semi-logarithmic and sigmoidal swelling laws to accurately simulate the observed heave in Staufen, and compares them against a previously developed HM model utilizing a linear swelling law. Comparative analysis demonstrates that the proposed models exhibit better capability in replicating the ground heave, with the linear model showing lower performance yet maintaining practical adequacy. Additionally, statistical analyses reveal the impact of geological complexity and spatial heterogeneity of rock properties on swelling behavior, providing crucial insights for engineering geologists and researchers. This study contributes to the development of informed strategies to mitigate risks associated with clay-sulfate rocks, thereby enhancing the stability of affected infrastructure.