Developement and Implementation of a hydro-mechanical model for unsaturated sands

• Applicant: Professor Dr.-Ing. Theodoros Triantafyllidis
• Subject Area: Geotechnics, Hydraulic Engineering ; Architecture, Building and Construction History, Construction Research, Sustainable Building Technology
• Term: from 2015 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251282961

In many engineering structures and geotechnical applications, the influence of the suction on the hydro-mechanical behavior of unsaturated soils is of interest for the analysis and prediction of their stability and deformations. For most of these applications, the suction can range from 0 up to 1000 kPa. In the special case of unsaturated sands the following shortcomings have been detected: the existing constitutive models inherit most of their concepts from the models for unsaturated clays leading to an overestimation of the material strength when approaching to the dry state. Within the suction range of interest, the capillary stress (suction times the degree of saturation) can result in large values. This makes the simulation of the material when selecting the Bishop stress as constitutive stress almost impossible. In addition, most of the experiments given by the literature show little information about the relevant parameters to calibrate the hydro-mechanical models for sands, such as the role of the suction in the void ratio at the critical state and in the stiffness. The current project proposes the performance of an experimental plan and the development and calibration of the numerical tools for the correct and appropriated simulation of unsaturated sands. It includes the development and implementation of new governing equations to circumvent the aforementioned shortcomings. The new governing equations and constitutive models will be evaluated through the simulation of physical models of an unsaturated sandy slope. At the end of the project, a complete set of experiments to calibrate the hydro-mechanical model for unsaturated sands will be available, and a set of open-free softwares for its correct simulation will be developed.

• DFG Programme: Research Grants
• Participating Persons: Privatdozent Dr.-Ing. Andrzej Niemunis; Professor Dr.-Ing. Torsten Wichtmann