Stabilisation columns (STS) are especially used for the foundation of structures with small to medium loads. As the columns are normally created with relatively small clearances, they are even suitable for the creation of a foundation for thin floor slabs. They are able to show their full strength when used on difficult soil layers of low to medium depths. When used in areas where there is an inclined layer course, they are able to reduce settlement differences to a minimum.
Their mode of action is based on a redistribution of the load from the soil to the stabilisation columns as is described in the "Merkblatt für die Herstellung, Bemessung und Qualitätssicherung von Stabilisierungssäulen zur Untergrundverbesserung" (Leaflet on the Manufacturing, Dimensioning and Quality Assurance of Stabilisation Columns for the Improvement of foundation soils). The stabilisation columns can be placed both in soil layers with a load bearing capacity and in such as do not have such a strong load bearing capacity.
First of all, a rod is inserted in the soil down to the required depth, whereby the insertion form can be freely selected in keeping with the the existing foundation soil situation. The rod is then removed during the pressing in of a mortar that is rich in solids. Due to its consistency and grainage, this mortar is able to displace the soil to the side.
Benefits of stabilisation columns
- low vibration when created with drilling
- no soil removal when created with ramming
- well suited for a concentrated load transfer with foundations in addition to the provision of extensive improvements under floor slabs
Information for design and execution
Information on the planning and execution of stabilisation columns is provided in the "Merkblatt für die Herstellung, Bemessung und Qualitätssicherung von Stabilisierungssäulen zur Untergrundverbesserung" from the German Geotechnical Society.