Deep Soil Mixing has used soil mixing solutions as an alternative to piling for the first time in the UK for a housing project in St Mary’s Bay, Kent.
The firm’s soil stabilisation techniques are being used across the whole site area under residential dwellings to prevent extreme settlements from variable ground.
According to Deep Soil Mixing, the works are shaving more than a year off the programme for a conventional “surcharge” solution as well as providing improved stability behind coastal defences.
Deep Soil Mixing has undertaken both column and mass mixing using a double rotary mixing head designed in house by managing director Robert McGall. The work involves installing soil mixed columns to a depth of up to 10m as well as a soil mixed mattress across the whole of the site covering an area of just under 11,000m².
The company has also used the cutter soil mixer to install 200 soil mixed panels.
st marys bay deep soil mixing double rotary auger soil mixing
The cutter soil mixer was specifically used on this project to overcome some isolated areas of very stiff layers of clay which had softer soils below, so it was necessary to mix through the clay into the soils below to enable remediation to take place.
This is the fourth time this bi-rotational mixing head has been used in the UK, according to the firm. The previous three occasions were when Deep Soil Mixing were on the Mersey Gateway Crossing in Cheshire, a retail park in Runcorn and more recently at Dover Harbour.
McGall said: “In response to a foundation enquiry from the consulting engineers Considine we put forward various options that soil mixing could provide to deliver a design solution that saved the client time and reduced cost comparable to alternative ground engineering solutions such as dig and cart away and piling.
“We always advise getting involved with clients and their designers as early as possible in their development process to create engineered solutions that offer real cost savings for projects including real benefits such as reduced vehicle movements and the efficient use of onsite materials on their projects, which reduces the carbon footprint and offers environmentally friendly sustainable solutions.
“The alternative solution was to either pile the buildings which would have created huge conflicts in differential settlement and the need to remove soil from the site and take it to landfill, which again was not a cost effective or environmentally friendly solution. Soil mixing is also quieter than piling and has zero vibration which meant there was no impact on the surrounding residents.”
deep soil mixing double rotary auger in operation at st marys bay
The brownfield site, close to a sandy beach, was once home to a former hotel and military base which has been demolished. When completed the scheme will consist of a range of houses and apartments and a landscaped coastal park area, car park and children’s play area.
The project is due to be completed later this year.