Soil mix - CSM wall

As a solution for the construction of a long, continuous retaining wall - its main area of application - the cutter soil mix wall (CSM wall) consists of adjacent or intersecting parallelepipedic panels. The panels are formed by intensive, in situ mechanical mixing of soil with a continuously injected hydraulic binding agent, usually cement. The retention function of the mixed soil CSM wall is induced by the development of arching after curing of the « soil-binder » mixture in between the steel profiles, inserted into the freshly mixed wall panels.

Construction sequence

In accordance with the requirements of standard  prEN 14679: “Deep Mixing”

1. In advance excavation of a guide trench approximately 0.5 m deep to accommodate the mix of soil and cementitious binder. Positioning of the cutter soil cutting-mixing head

2. Drilling to a depth of approximately 1 m and controlling the verticality

3. Fracturing of soil during driving of the cutting tool and simultaneous injection of a mix of water and a cement-based binder.

4. After reaching the design depth and during the extraction of the cutting-mixing head, blending and homogenization of the soil with the injected cement grout / slurry. Depending on the nature of the soil, the panel will be mixed once again.

5. Insertion of the reinforcement (steel profiles) in the fresh soil-cement mixture.

6. By repeating the procedure, the formation of the CSM wall progresses by intersecting the previously made panel.

Possibility of real-time electronic monitoring of the construction parameters ensuring optimum quality control.

Construction chart

Fields of application

• Suitable as an earth retaining wall and cut-off wall solutions (phases 1 to 6), or as a soil improvement technique (phases 1 to 5 of the installation process).

• The placement of reinforcement beams such as steel profiles, inserted to withstand the shear and bending stresses acting on the retaining wall, ensures the load-bearing function of the wall and optimizes its stability.

• Alternative solution to the ‘Berlin’ retaining wall or the pile wall

• Favourable in sandy soils with limited fine grain distribution fraction (less suitable application in silty and clayey soils)

Environmental impact

• Discharge of the soil-cement slurry, no removal of soil, very little spoil is generated

• Vibration-free

• No noise pollution

• The slurry handling plant for mixing and pumping requires an working area of at least 100.

Technical specifications

• CSM wall thickness: standard 0.55 m

• Depth: standard less than 20 m

• Blending of the in situ soil with a mix of water and cementitious binder by using a vertical axis equipped with compact hydraulic motors housed inside two sets of rotating drums while drilling, cutting and remoulding the surrounding soil and at the same time mixing the cement slurry with the loosened soil. Each of the two counter rotating cutting wheels rotate independently. No casing is used.

Related projects for this technique

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