Deep Soil Mixing

Deep Soil Mixing (DSM) is a ground improvement technique that takes place in-situ which can be used to improve the engineering properties of soils, including peat, which are considered to be soft or very soft to depths of up to 25 metres.

The technology is commonly used in Scandinavia, Japan and New Zealand as a foundation solution for roads, railways and buildings. More specifically, in areas of the world which can be affected by earthquakes, deep soil mixing can be used to help prevent soil liquidation.

We have adapted the techniques and the equipment that is required to better suit the soil conditions we more commonly encounter in the UK.

The Process

Our processes involve mechanically mixing a wet cementitious grout with the soils to produce either soil-cement columns or a mass block of improved material. The result is a massive increase in compressive and shear strength within the improved materials. In the case of soil-mixed columns, we can design and provide a composite ground improvement solution which offers enhanced stiffness characteristics, allowing the DSM columns and the surrounding soils to share the imposed loadings and settle uniformly. This high pressure wet soil mixing system has a wider range of working parameters when compared with dry soil mixing.


  • Fast – ground improvement can support advancing equipment and structures within one day.
  • Safe – the in–situ method avoids the requirement for significant deep excavations and the associated hazards.
  • Sustainable – this approach avoids the requirement to dispose of unsuitable material and the importation of aggregate.
  • Adaptable – compact equipment with fast set-up time means the process can be utilised for a wide range of projects from the smallest up to multi million pound schemes.
  • Technical – increases allowable bearing pressure, controls settlement and reduces soil permeability.


  • Road and railway embankments
  • Building and house foundations
  • Storage tanks
  • Slurry cut-off walls
  • Hardstanding’s
  • Bridge abutments
  • Retaining walls
Read more about our techniques below...