The GeoNail system is an in-situ soil reinforcing technique used to stabilise slopes or excavations.  Steel bars are installed and grouted into the soil mass on a closely spaced grid to produce a zone of reinforced soil or rock.  This enables the soil mass to act as a homogenous unit which retains the unsupported soil behind in a manner similar to a gravity retaining wall.  A secondary support, usually in the form of a lightly reinforced gunite skin, is normally applied to contain the soil between GeoNail positions.

Positive Features

  • Extremely cost effective system under suitable conditions
  • Can be installed faster than most other comparable lateral support systems
  • No load transfer structure required onto face of excavation being supported
  • Easily adaptable to changes in site conditions
  • Relatively simple inexpensive procedures can be used to provide corrosion protection of permanent GeoNail installations

Other Considerations

  • Generally not suitable for deep seated failure surfaces or high surcharge loads
  • Not suitable in non-cohesive strata below the water table
  • Usually not economical in soft clays or boulder formations.
  • The GeoNail System can be used for both temporary and permanent support.

Variations in Installation Techniques

An application that is becoming more common in basement excavations is to use the total GeoNail system or the gunite wall as the permanent basement structure.  The gunite wall is designed to span between suspended floors as well as carrying vertical loads where necessary.

All GeoNails are installed by Franki in accordance with SAICE Code of Practice (1989) for Lateral Support in Surface Excavations following Franki’s Standard ISO 9001 procedures.