Ground Improvement

Kiewit’s ground improvement methods comprise five main areas: aggregate piers, vibro compaction, cutoff walls, grouting and soil mixing. All five of these sections are outlined below along with links to some of our work.

Aggregate Piers

Aggregate piers (also called stone columns or aggregate columns) are a ground improvement method that uses compacted aggregate to create stiff pier elements. Aggregate piers help increase bearing capacity, shear strength, rate of consolidation, liquefaction resistance and reduce settlement. Typically they are used in sands and unstable soils.

Aggregate Piers

  • Rapid installation
  • Cost effective compared to other foundation options
  • Creates additional drainage paths
  • Allows for high level of compaction
  • Efficient QA/QC procedures

Vibro Compaction

Vibro compaction is a ground improvement method that densifies deep cohesionless soils to increase bearing capacity, increase shear strength, reduce settlement, and increase liquefaction resistance. This technique is typically used in cohesionless soils. Applicable soils include clean sands with less than 15% silts and/or less than 2% clay.

Vibro Compaction

Advantages

  • Cost effective compared to other foundation options
  • Effective above and below the water table
  • Faster than other foundation options
  • Can increase angle of internal friction by 5-10 degrees

Slurry Trench Cutoff Wall

A slurry trench cutoff wall is a technique used to restrict horizontal movements of liquids. Construction involves digging the wall under a bentonite or polymer slurry with a long stick excavator or clamshell and replacing the removed material with a low permeability material. The low permeability material is often a mix of cement, bentonite, and soil. This technique is used to control groundwater seepage into an excavated area for temporary or permanent applications. The technique is also used frequently to prevent seepage in dams.

Slurry Trench Cutoff Wall

Advantages

  • Efficient QA/QC procedures
  • Easy to check depth and confirm that excavated materials are in desired stratum
  • No joints between panels or construction segments

Grouting/Jet Grouting

There are many types of grouts and grouting techniques used for a variety of applications. We have experience in chemical, permeation, pressure, and curtain grouting. Please contact us to discuss what options work best with your project’s needs.

Grouting/Jet Grouting

Advantages

  • Can work in tight working conditions and low-overhead
    environments
  • Computer monitoring of grouting shows real-time analysis of
    construction process
  • Can be used in most soil types
  • Can be installed under existing structures

Soil Mixing

Soil Mixing (also called mass stabilization) is a technology to stabilize and strengthen soils at shallow to moderate depths using a binder material. Mass mixing methods can be used to treat soft clays, peats, sludges, and dredged material. Typical uses for this technique include roadway and railway embankment, and support of structures.

Soil Mixing

Advantages

  • Can be used to stabilize peat and other soft soils, and to treat contaminated soils
  • Can stabilize large blocks of soil
  • Quicker and less expensive that many other alternatives (such as mass replacement)
  • Lower environmental impact than other solutions
  • Traditional binders of common materials