Deep Soil Mixing (DSM) Services

Deep Soil Mixing (DSM) involves the injection of binder agents to mix with the soil and form columns to reinforce the ground.

The method of the Deep Soil Mixing column was invented in Japan in 1970s and since then it has been gaining the increasing popularity all over the world as a ground improvement method to stabilise soils with low bearing capacity.

Presentation and key elements

Description

The principle of the Deep Soil Mixing (DSM) is to improve the strength properties of the soil by mixing it with the binder (cement slurry, cement-fly ash slurry or bentonite). As a result, a solidified mixture of soil and cement is created with considerably higher strength and mechanical parameters.

The installation of DSM columns involved the introduction of a rotating auger into the subsoil which destroys the soil structure and mixes it with the injected binder. Typically, augers consisting of a drilling rod and cross bars are used. The soil mixing process is aided by injecting the cement binder through nozzles located at the end of the drilling rod. The column formation stage starts after reaching the designed depth. This is usually divided into several stages where the auger is lifted and lowered to ensure adequate mixing of the soil with the binder and to form a homogeneous column.

Application

Deep Soil Mixing (DSM) columns may be successfully applied as the improvement for the footings, bridge abutments, wind turbine foundations, excavation lining, etc. Wherever silty and sandy soils exist the application of this technology is particularly beneficial.

The length and arrangement of the columns will vary depending on the load transferred to the columns and maximum allowable deformations of the structure. Due to the lack of soil movements and vibrations during the column forming process, this technology is perfectly suited for stabilisation of the subsoil nearby existing buildings or facilities.

Advantages

High bearing capacity in non-cohesive soil: Deep Soil Mixing (DSM)columns formed in non-cohesive soils have high bearing capacity values (strength values of the cement-soil mixture can be up to 6 MPa).

Various installation pattern: possible to form the columns in blocks, groups, linearly and cells to suit different structures.

Multiple Deep Soil Mixing (DSM) columns: possible to install two or more augers on a rig to accelerates the installation work.

When and why use Deep Soil Mixing?

The principle of Deep Doil Mixing is to improve the strength properties of a weak soil (clay, silt and/or sand) by mixing it with the binder (e.g., cement slurry, bentonite, lime, etc.) to form a solidified mixture of soil and cement with a considerable higher strength and mechanical parameters. It is a very flexible technique adopted mainly to increase bearing capacity, reduce settlement and mitigate liquefaction.

Menard's tip

Binder dosage and mixing parameters are selected according to soil characteristics and specifications to be achieved. Typically, laboratory trial mixes are to be followed with field calibration at project site.

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