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Detecting the Position of Impermeable Membranes Buried in the Subsurface
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 1st Conference on Geophysics for Infrastructure Planning Monitoring and BIM, Sep 2019, Volume 2019, p.1 - 5
Abstract
PVC membranes are used as groundwater barriers in infrastructure works in situations with high groundwater levels. When reconstruction works are necessary, the position of the membrane in the subsurface needs to be known. Deltares developed a method based on Electrical Resistivity Tomography (ERT) using the high electrical resistivity of the PVC membrane. Modelling showed that the PVC membrane has a profound effect on the electrical field lines. Classical ERT employed from the surface does not have sufficient spatial resolution to locate the membrane. Electrodes need to be closely spaced and within ca. 1.5 m from the membrane. To this end, a prototype tool was developed that can be pushed in the ground and measure while approaching the membrane. This prototype was tested in the laboratory. Measurements at different distances from the membrane showed that the tool can detect the distortion of field lines. Inversion was used to pinpoint the position of the membrane within 10 cm. The next step is to develop a tool that can be used in the field.