Soil Mixing

Dry Soil Mixing

Dry soil mixing is a low-vibration in situ process used to improve the engineering properties of soft clays, peats and other weak soils. This method is best suited to soils with a high moisture content (greater than 25% and near liquid limit). During the soil mixing process, cementitious binders incorporated in the soil, bond the soil particles together, thereby increasing shear strength and reducing compressibility. The process may be used to created columns or panels of treated soil or to treat the entire soil mass, depending on the application. Treatment depths can extend to over 75 ft. For column construction, the base rig (either a tracked drill or crawler crane to provide stability) is fitted with a mast-mounted drill rod and mixing tool that mixes the soil and binder as the drill rod is rotated by means of a high-speed motor. For mass mixing, a modified backhoe is fitted with a horizontal axis mixing tool.

Advantages

  • Allows development of otherwise time and cost-prohibitive sites
  • More time efficient than pre-loading
  • Typically more economical than remove and replace
  • Low noise and vibration
  • Site dewatering not required
  • Minimal spoils generation

Applications

  • Structural support
  • Embankment support
  • Slope stabilization
  • Marine and harbor development

Wet Soil Mixing

The wet soil mixing method extends the range of soils that can be improved with mixing technology. An engineered grout slurry is introduced into the in situ soil via the hollow stem of the mixing shaft as the tooling advances and rotates to design depth and is then withdrawn to the surface. The process creates stabilized soil-cement columns that can be designed as individual foundation elements or clustered to construct larger geometries.  Wet soil mix columns can be constructed to depths of up to 100 ft.

Advantages

  • Allows development of otherwise time and cost-prohibitive sites
  • Typically more economical than remove and replace
  • Accelerates the construction schedule
  • Low noise and vibration
  • Excess soil-cement product may be used as fill material
  • Can solidify and stabilize contaminated sites

Applications

  • Structural support
  • Slope stabilization
  • Marine and harbor development
  • Liquefaction mitigation
  • Excavation support
  • Water cut-off

TRD Soil Mix Walls

Trench cutting and remixing deep (TRD) soil mix walls can be constructed in soils ranging from soft organics to dense sand with cobbles. This technique differs from other in situ soil mixing system in that it delivers an engineered, continuous wall by vertically mixing the entire soil profile, thus eliminating any pre-existing stratification. Wall widths range from 22 to 33 in. and can be constructed to depths of up to 180 ft. Mixing is accomplished by a chain-saw-like cutter post mounted on a base unit. Additional post sections are added as the tooling advances to design depth.  As the unit travels along the horizontal alignment of the wall, the rotational cutter chain cuts and mixes the soils with a cement-based slurry via ports near its tip. Since the cutter post is inserted in sections, the base unit presents a low profile, making if possible for TRD walls to be constructed in low headroom situations.

Advantages

  • Compact, low headroom equipment
  • The wall is continuous throughout the soil profile
  • Environmentally friendly
  • Low Vibration

Applications

  • Groundwater cut-off walls and seepage control
  • Earth retention and excavation support
  • Structural support
  • Liquefaction mitigation
  • Contaminant containment
  • Barrier walls for settlement mitigation during tunneling