Electrical resistivity characterization and defect detection on a geosynthetic clay liner (GCL) on an experimental site |
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| Institution: | 1. Univ. Bordeaux, I2M, UMR 5295, F-33400 Talence, France;2. Departamento de Matemáticas, Área de Matemática Aplicada, C/Calvo Sotelo S/N, 33006 Oviedo, Spain;1. Department of Petrology, Geochemistry and Geological Prospectio, Universitat de Barcelona, Martí i Franquès s/n, 08030 Barcelona, Spain;2. Department of Geology and Environmental Earth Science, Miami University, 501 East High Street, 45056 Oxford, OH, USA;3. Ecole Nationale des Sciences Appliquées d''Al Hoceima (ENSAH), University Mohammed Premier, Ajdir, Al Hoceima, Morocco;4. Department of Agriculture, Ranching and Environment, Diputación General de Aragon (DGA), Plaza de San Pedro Nolasco, 7, 50071 Zaragoza, Spain;1. State Key Laboratory of Geohazard Prevention and Geoenvironmant Protection, Chengdu University of Technology, 1#, Dongsanlu, Erxianqiao, Chengdu 610059, Sichuan, PR China;2. Univ. Grenoble Alpes, Univ. Savoie Mont Blanc, CNRS, IRD, IFSTTAR, ISTerre, 38000 Grenoble, France;3. Department of Mechanics, Harbin Institute of Technology, Harbin, People''s Republic of China;4. IRSTEA, Aix-en-Provence, France |
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| Abstract: | In this paper we analyze the onsite characterization of a geosynthetic clay liner (GCL) that serves to ensure the impermeability of a landfill cap by DC electrical methods. The imaging of the GCL geoelectrical properties is a challenging problem because it is a very thin (between 4 and 7 mm thick) and resistive layer (from 100,000 to 2,000,000 Ω·m) depending on meteorological conditions and aging. We compare results obtained using electrical resistivity tomography (ERT) using two different kinds of arrays (dipole–dipole DD and Wenner–Schlumberger) on an experimental site with engineered defects. To confirm these results and to find the real onsite GCL resistivity we have performed sampling of the posterior distribution of this parameter using vertical electrical sounding (VES) inversions. Different VES methods were extracted from ERT with DD array and converted into a Schlumberger array.As a main conclusion the dipole–dipole array provides a better resistivity resolution of the defects than the Wenner–Schlumberger array. On ERT images, the defect detection seems to be impossible if the GCL has very high resistivity, as it happened when it was put in place. Taking into account the equivalence rules, the inversions are in both cases (ERT and VES) compatible. The GCL resistivity estimated from PSO (particle swarm optimization) varies from 3.0 105 to 1.106 Ω·m depending on saturation conditions during the twenty first months of its placing. Then, the resistivity dropped to 4.104–9.104 Ω·m, indicating a probable chemical damage of the GCL due to aging. Finally the fact that the VES inversions are solved via PSO sampling allows for the detection of a very thin and resistive layer and opens the possibility of performing micro VES surveys along the landfill to detect possible GCL defects. |
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