Abstract
Increased intensity of rainfall in later years seems to result in increased frequency of rainfall-induced landslides in natural slopes with glacial Quaternary deposits, which cover large parts of Norway. Many slides hit railway and road infrastructure, and sometimes dwellings. Typically, the soil matrix has a high content of intermediate soils (sand and silt). Natural soil slopes may have inclinations above the effective friction angle of the soils. Slope stability hence must rely on some cohesion, which often is “apparent”, i.e. caused by negative pore-water pressure (suction). Dissipation of suction during short- or long-term rainfall hence results in reduced shear strength of the slope, and may lead to slope failure. There is a scarcity of data for Norwegian soils for thorough analysis of landslide triggering based on unsaturated geomechanics. More data may result in improved landslide warning. In this paper, results from unsaturated shear box testing of samples of a silty sand taken from a landslide site in Eastern Norway are presented and discussed.
Highlights
Soils encountered in Norway are predominantly of Quaternary origin
Sandy and silty slopes are vulnerable to subsequent erosion, if surface water finds its way into the landslide scar, and especially so if the vegetation cover first has been damaged or removed
In situ tensiometer measurements down to 1.2 m at the time of soil sampling confirmed that suction up to approx. 25 kPa was present in the soil (Figure 3), in the order of 10 kPa in the sand specimens tested, and just below 25 kPa in the silt layer
Summary
Soils encountered in Norway are predominantly of Quaternary origin. Marine clay and silt were deposited in the sea. The former seabed has later been lifted onshore by isostatic uplift when the glaciers covering Northern Europe gradually melted. The marine limit of today's landscape, other types of glacial sediments are encountered, primarily till and glacio-fluvial deposits, and to some extent glacio-lacustrine deposits. In addition to these two groups, post-glacial deposits of all varieties are encountered, like fluvial deposits, colluvium, scree/talus, landslide debris and sometimes eolic sediments
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
