Improved geotechnical properties in salt-treated highly sensitive landslide-prone clays

Retrogressive or progressive landslides in slopes with highly sensitive quick clays may extend several hundred metres from where the slide was initiated. Reintroducing high salt contents to the pore water of leached low-saline quick clays may inhibit the development of such large landslides. Wells filled with potassium chloride (KCl) were installed in a quick-clay deposit at Dragvoll, Trondheim, Norway, to investigate the impact of changed pore-water chemistry on the geotechnical properties. The clay ceased to be quick due to favourable changed ion composition in the pore water, even at low salt contents, thus inhibiting retrogressive development. The apparent pre-consolidation stress (p′ c ) increased with increasing salt contents and the immediate collapse in structure typically seen in quick clays was avoided at loads just beyond p′ c by changing the pore-water chemistry. Quick clay treated with KCl may therefore work as a barrier against retrogressive development and reduce the risk of initiation of progressive landslides.