KFS Finland Oy executed the pit support for the new Ratina shopping center with sheet piles. In addition, pit support close to the existing bus station building was done with jet grouting underpinning and anchors.
The basic design of the jet grouting with 80 cm columns was changed to two meter columns because of an excavation depth up to 13m with four rows of anchors.
The bus station was fully operational during the construction so a permanent measurement system of hydrostatic water level cells was installed to ensure a fast reaction in case of any settlement. Over the whole time of observation recognized movements were below five millimeters.
The deepest parts of the excavation were below the ground water surface level, therefore a sealing slab with jet grouting was necessary. The diameters of the columns were three meters to ensure a cost effective and time effective execution of the works. In total the sealing slab was over 20.000 m2 and so it was one of the biggest sealing slabs that have ever been executed in Europe with jet grouting.