Duration: 01.03.2009-28.02.2012 Project funding reference number: WA 2112/2-1, SCHE 1604/2-1 Project leader: Dr. Norman Wagner , Dr.-Ing. Alexander Scheuermann Project partner: Institute of Material Research and Testing at the Bauhaus-University Weimar (MFPA) Geotechnical Engineering Centre, the University of Queensland (UQ) University of Karlsruhe (TH), Karlsruhe Institute of Technology (KIT) Institute for Soil Mechanics and Rock Mechanics Foundation: German Research Foundation (Deutschen Forschungsgemeinschaft, DFG)
High-frequency electromagnetic measurement techniques are used to quantify spatial and temporal variation of soil moisture within scientific and practical issues of geotechnics, hydrology and soil physics. Precise knowledge of the frequency dependent electromagnetic material properties is urgently necessary for successful utilization of these methods. However, in most applications this is not sufficiently taken into account.
Interface effects lead to a number of dielectric relaxation processes: free and bound water phase, Maxwell-Wagner-effect and counterion relaxation effects. These relaxation processes are the reason for the strong frequency dependence of the electromagnetic material properties below 1 GHz. The matric potential is a measure of the bonding forces on water in the soil. For these reasons, in fine grained soils the bound water phase is the link between the hydraulic and dielectric soil properties.
The main objective of the project is the development of new analytical methods for a derivation of the structure and texture dependent coupled dielectric and hydraulic properties of mineral soils. For these reasons an experimental setup will be developed for a simultaneously determination of the water retention characteristics as well as the dielectric spectra of soils in a broad frequency range (1 MHz - 10 GHz) under controlled conditions.