Abstract
Identification of sediment types and in particular delineation of leached, possibly sensitive marine clays is of crucial importance for geotechnical design of infrastructure projects in Norway. Since leached clays normally have a lower salt content than intact marine clays, the electrical resistivity is consequently higher, and thus clay characterization may be based on data from high-resolution airborne electromagnetics (AEM) collected from helicopter. However, the resistivity difference between leached and unleached clays is small compared to the transition to bedrock and may furthermore vary locally. Therefore, indication of leached clays based on resistivity data has so far been done by manual interpretation. Here, we present a new procedure to calculate the likelihood of possible sensitive clays directly from AEM data. Geotechnical ground investigations are used to locally determine the expected resistivity of sensitive clay. The computation results are compared with well-known quick clay zones. The procedure is not intended as a simple solution to delineate quick clay, but to evaluate an area’s likelihood of sensitive clays that can be used as a cost-saving tool to efficiently place geotechnical investigations.
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References
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Acknowledgements
The Norwegian National Rail Administration is acknowledged for the permission to publish the field data shown in this paper and for financing most of the reported developments. The authors would like to express their gratitude to Helge C. Smebye, Malte Vöge and Guillaume Sauvin for important contribution to the initial data processing phase, to Håkon Heyerdahl, Toril Wiig and Anne-Lise Berggren for valuable comments in the algorithm development phase and to the reviewer Thorleif Dahlin for his comments to this paper.
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Lysdahl, A., Pfaffhuber, A.A., Anschütz, H., Kåsin, K., Bazin, S. (2017). Helicopter Electromagnetic Scanning as a First Step in Regional Quick Clay Mapping. In: Thakur, V., L'Heureux, JS., Locat, A. (eds) Landslides in Sensitive Clays. Advances in Natural and Technological Hazards Research, vol 46. Springer, Cham. https://doi.org/10.1007/978-3-319-56487-6_39
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DOI: https://doi.org/10.1007/978-3-319-56487-6_39
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