Innovative First For Soil Mixing Enabling Construction Of Gull Wing Bridge In Lowestoft
Innovative First For Soil Mixing Enabling Construction Of Gull Wing Bridge In Lowestoft
Environmentally friendly solution deep soil mixing was recently used on the new Gull Wing Bridge in Lowestoft by Deep Soil Mixing Ltd who recently carried out soil mixing solutions for client Farrans, to stabilise the site ground and ensure the successful completion of the project.
Deep Soil Mixing Ltd was responsible for improving the strength, condition and stability of the soil on the northern approach to the new Gull Wing Bridge, to ensure its load bearing quality, this was achieved with the native soils through a combination of mass mixing and the installation of Soil Mixed Columns (SMCs).
Specified for its environmental qualities the soil mixing solution meant none of the existing site soil was excavated and removed from the site thus reducing the carbon footprint of the project and saving on time and costs. It also aided Health and Safety as there were less vehicle movements on site.
The ground was mass mixed to depths of 2 metres and soil mixed columns were installed to depths of 7 metres. Using Deep Soil Mixing Ltd’s double rotary mixing head that rotates in two directions to provide homogeneous mixed ground. This enabled greater accuracy of mixing to improve efficiency and cut costs for Farrans compared to using the industry standard of a single auger mixing head.
As part of the soil mixing solution, Deep Soil Mixing Ltd created bridge abutments to improve the load bearing pressure of the ground and resolve any contamination in the ground. The process involved raising the embankment soils by approximately 5.5 metres above the existing ground and using this soil heap to mix a 5-metre mattress above ground level. Soil mixed columns were installed within 50mm of water assets, which meant ensuring a 1 metre gap between the teeth of the rotary mixing head. The rotary was then reduced to 900mm in diameter before the ground was mass mixed to within 1 metre of the crown of the assets.
The soil mixed columns were installed through the soil mixed mattress, ensuring the binding of the columns into the platform turned it into the transfer mattress between the soil mixed column layout. This innovative solution was a first in the UK and enabled testing to be carried out to prove there was no punching of the soil mixed columns.
The mix of mass mixing and soil mixed columns provided the necessary support to the northern approach embankment and enabled the bridge to be built once the soil mixing phase had been completed.
