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3-d site investigation using GPR and ER tomography with pneumatic borehole electrodes


We present a field study for geophysical site investigation using a novel pneumatic downhole electrode system for hole-to-hole electrical resistivity tomography (ERT) as well as surface ERT, ground penetrating radar (GPR) and cross-hole GPR tomography. The aim of the investigation was to delineate zones of artificial and potentially contaminated filling and the main geological layers on a former industrial area, now the largest urban reintegration project in Switzerland (Zentrum Zurich Nord). Results of geophysical imaging proved highly consistent with traditional site investigation techniques, such as cone penetration tests and core drillings, but yielded spatial information at much lower costs. The 3D images allowed the volume of potential excavations to be calculated and may reduce the costs for future probing. The modular pneumatic downhole tool is designed to push various sensors through dedicated casings, e.g. sensors for quantitative analysis of volatile organic compounds, which will be employed at a later stage of the project to complement the images of physical quantities.


Friedel, Sven and Wotschke, Peter and Hermanns Stengele, Rita

Index Terms:

Soil; borehole geophysics; resistivity; GPR; contaminated sites; SoilGroup; ClayGroup; Friedel, Sven; Hermanns Stengele, Rita; Wotschke, Peter

Further Information:

Date published: 2003