Future Strategy for Soil Investigations in Quick Clay Areas

The landslides at Rissa in 1978, and more recently at the Skjeggestad bridge in Norway, are devastating reminders of the potential threats related to quick clays. For a geotechnical engineering project it is hence important to determine if there is sensitive clay present and to clarify the extent of the quick clay deposit. Integration of geophysical and geotechnical methods has become more common in ground investigations nowadays, particularly in larger projects. In such integrated measurements, geotechnical engineers and geophysicists can cooperate, and by joint knowledge decide where geotechnical soundings, in situ tests and sampling should be located with optimal cost-efficiency. This paper describes how various investigation methods may be combined to achieve a successful strategy for detecting deposits of quick and sensitive clays. The methods presented herein include conventional soundings, CPTU and field vane test (FVT), supplemented by geophysical methods such as CPTU with resistivity measurements (R-CPTU), Electrical Resistivity Tomography (ERT) and Airborne Electromagnetic Measurements (AEM).