Characterization of two sites for geotechnical testing in permafrost: Longyearbyen, Svalbard

Abstract

The mean annual air temperature in Svalbard has increased between 3 ℃ and 5 ℃ during the last 40 to 50 years. The continuous warming trend observed in Svalbard during the last 30 years has raised concerns about the stability and durability of existing infrastructure on permafrost and uncertainties related to the design of new structures and infrastructure in the region. It is therefore of special interest and importance to establish a reference field site for geotechnical testing in permafrost in Svalbard. Two benchmark sites are established near Longyearbyen, Svalbard (78°13'N, 15°28'E) for geotechnical testing and evaluation of field investigation methods in saline, permafrost soils. These sites, named “Adventdalen” and “UNIS East” based on their locations, form part of the research infrastructure of the Norwegian GeoTest Sites project. Since 2016, efforts have focused on geotechnical and geothermal characterization and instrumentation of the upper 30 m of the soil stratigraphy. Field investigations included drilling and core retrieval, installation of thermistor strings, CPTU, and ERT. Laboratory investigations focused on index testing and the evaluation of soil thermal properties. This paper characterizes soil conditions at these sites and may serve as a reference for others working with saline, permafrost soils.