ABSTRACT
At Ullånger, about 500 km north of Stockholm, a new alignment of road E4 was constructed in 1993 close to and upslope the old road. The soil consists of silt and clay with a maximum thickness of 8 metres. Artesian ground water condition occurs. During the construction work an 80 m long crack and vertical movement of 20 cm indicated that a slide movement was developed in the old road. In order to stabilise the slope lime-cement columns were installed. The column layout was designed as slabs of set perpendicular to the road alignment. Due to the low slope stability observations of horizontal surface deformations and ground water level were carried out. During the installation of the columns large horizontal deformations - up to 300 mm - and raised ground water levels were registered. The original plan for installation sequence of the column slabs had to be. The rate of deformation and rise in ground water level were closely connected to installation work.. The observation system was of great help for surveillance and guidance of the installation work.
