Vibro replacement – Sustainable solution for ground improvement in soft clays

Vibro replacement is globally a widely adopted ground improvement method. This technique uses a bottom feed vibrator, penetrating fine soil (clay, silt and fine to medium sands) and filling the created space with crushed rock or gravel densified by the vibrator.

As a result, a so-called stone column remains in the ground. The stone columns will be stronger, stiffer and more permeable than the surrounding soil, thus, improving the soil behaviour regarding bearing capacity, settlement response and drainage.

In Norway, vibro replacement has, so far, received scant attention, likely due to very challenging ground conditions such as soft and sensitive clays (i.e., quick clay). Today, it is still uncertain if vibro replacement can be reliably performed in very soft clays and result in the required improvement.

The latest research indicated that vibro replacement is a more sustainable ground improvement method than deep soil mixing and bored, cast in-situ piles and can be increased by utilizing recycled aggregates as stone column fillers.

The research project VIBro rEplacement (VIBE)

The project VIBE, initiated by Keller Geotteknikk in cooperation with the Norwegian Geotechnical Institute (NGI), investigates if vibro replacement with recycled raw material is a suitable ground stabilisation solution in Norwegian clays by 

• executing a full-scale test site at Onsøy (installation and loading of vibro stone columns, considering an extensive monitoring set-up)
• validating design guidelines using data from the test site and numerical simulations and
• assessing the environmental impact of vibro replacement with secondary aggregates.
   

The master's student investigates the possibilities and limitations of vibro replacements in soft soils in strong collaboration with the Norwegian Geotechnical Institute (NGI).