New loading system and measurement equipment for an existing testing pit

• Subject Area: Construction Engineering and Architecture
• Term: Funded in 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 468158261

The increasing diversity and complexity of problems in the field of geotechnical engineering and the claim for an economical and sustainable use of geomaterials (soil and rock) and soil-like materials (e.g. mineral materials, RC-materials, industrial by-products, waste from industry and incineration plants) require a much deeper understanding of their mechanical behaviour, as observed experimentally. Despite of the scientific effort in the last decades, the development and validation of models to simulate the complex coupled hydro-mechanical response of multiphase geomaterials still belongs to the most challenging fields of research in geotechnical engineering. In order to achieve the goals of research proposals, an extension of the experimental capabilities of the Zentrum Geotechnik of the Technical University of Munich for the comprehensive examination of the coupled hydro-mechanical behaviour of soil and soil-like materials under cyclic, alternating and dynamic loadings is imperative. The focus of the required equipment lies primarily on the investigation of the behaviour during shear loadings at either controlled or monitored boundary conditions. The experiments to be carried out with the new equipment have to cover the large range of shear strain amplitudes, stress paths, pressures and drainage conditions, which are relevant for the different geotechnical problems under consideration. So far, the testing equipment available at the Technical University of Munich and at universities in Bavaria does not satisfy all these requirements. Therefore, the testing facility described in this application is of strategic importance for the future research in Bavaria. This grant application aims for the partial funding of a new loading system as well as measurement equipment for testing large-scale models that can be set up in an existing testing pit. Within the 8 m deep testing pit geotechnical boundary value problems can be examined under cyclic and dynamic loadings up to 1.500 kN. Further components of the testing facility are a Resonant Column Device (in short: RC-device), a Cyclic Dynamic Triaxial Testing Device (in short: DTX-device) and an Omnidirectional Simple Shear Device (in short: ODSS-device). In the ODSS-device, the cyclic, alternating and dynamic loadings is be applied by controlling either the shear strain or the shear stress in two kinematically independent directions of shear deformation. The ODSS-device as well as the DTX-device allows the investigation in the range of medium to large shear strain amplitude. In contrary to the ODSS-device the DTX-device controls stress and strain in the principal directions while the rotation of the principal directions in the sample is one of the features using the ODSS-device. In the RC-device, the stiffness and hysteretic damping in the range of small shear strain amplitude can be determined by bringing a cylindrical sample into resonance.

• DFG Programme: Major Research Instrumentation
• Major Instrumentation: Erneuerung der Belastungseinrichtung und Messtechnik an einer bestehenden Versuchsgrube
• Instrumentation Group: 2940 Spezielle Baustoff- und Bodenprüfgeräte, Schergeräte
• Applicant Institution: Technische Universität München (TUM)
• Leader: Professor Dr.-Ing. Roberto Cudmani