Deep soil mixing for Whiteman Bridge, Reid Highway Extension, Middle Swan, Perth

The Reid Highway Extension project from West Swan Road to Great Northern Highway in Perth, Australia was completed in February 2010. The project includes a new bridge over the Swan River, named the Whiteman Bridge, and associated bridge approach embankments of about 8 m height. The approach embankments are underlain by a relatively weak and compressible silty clay/clayey silt zone of up to 4 m thickness. This stratum was predicted to undergo relatively large time-dependent settlements unless ground improvement was carried out. To alleviate the effect of relatively large time-dependent differential settlements between the bridge abutment and bridge approach embankment, Deep Soil Mixing (DSM) ground improvement was carried out below the approach embankments and abutments, combined with surcharge preloading of the approach embankments. This ground treatment enabled the abutments to be supported on shallow spread footings.