Diaphragm Walls

Since the 1980s Nicholson Construction Company has been constructing diaphragm walls to create permanent foundations and temporary earth retention walls for deep basements.  Nicholson’s long standing expertise in this technique was greatly enhanced by the 2005 merging of Soletanche, Inc. into Nicholson by our new parent Soletanche Bachy.

Soletanche, Inc. was active in slurry wall construction in the U.S. since the 1960’s and introduced hydrofraise technology in the 1980s.  As the core technique for their U.S. operations, slurry walls were completed for major projects at Fontenelle Dam (Wyoming), Navajo Dam (New Mexico), Arkansas Dam II (Arkansas) and Mud Mountain Dam (Washington), which set a world record depth of 400 feet.  

Diaphragm walls can be used for earth retention schemes for highway and tunnel projects, as permanent walls for deep shafts for tunnel access, and as permanent cut-off walls through the core of earth dams.

As construction in areas with dense and historic urban infrastructure becomes increasingly common and difficult, Nicholson understands the intense considerations involved in these situations where a very rigid earth retention system is required. Our team of engineers will then utilize diaphragm walls for projects where movement control is critical, where groundwater is present and makes conventional shoring difficult, or where dewatering is not practical.

Diaphragm walls (also known as slurry walls) are basically deep trenches excavated in the soil into which reinforced concrete is placed. Excavation is accomplished by digging panels into the ground using mechanical or hydraulic clamshell grabs or hydrofraise mills, while the trench stability is maintained using thixotropic suspensions of bentonite or polymer slurries.

Once excavated, three-dimensional reinforcement is set in the trench and followed by the placement of structural grade concrete using tremie pipes. The result is a structural wall system that not only provides temporary earth support, but also provides the permanent foundation system.  

The trenches are usually 2' to 4' thick and can be hundreds of feet deep, although few extend beyond 150'. They are formed in individual panels from 8' to 25' long and, when contiguously completed, can total thousands of feet in length or perimeter.

Nicholson Construction Company also uses these same techniques to form individual panels of various shapes including I, T, X or L. These shaped panels are also called barrettes and can accommodate top-down construction.

For more information on Nicholson’s expertise in the use of diaphragm walls or any other specialty techniques, please call 1-800-388-2340 or contact us today.

THE FACTS

Common Uses of Diaphragm Walls

  • Structural support for the construction of building basements with underground parking.
  • Add stability to landslides, highway cuts and deep building excavations including circular shafts.
  • Provide retaining walls in areas where severe limitations may be posed by noise, vibration, geology, water table and schedule.
  • Provide deep diaphragms where geometric precision and continuity at depth are vital for structural and hydraulic reasons.


Benefits of Diaphragm Walls

  • Can be installed through virtually all soil conditions, to any plan geometry and to considerable depths.
  • Can be constructed ahead of time and independent of other site activities.
  • Structural stiffness provides reduced ground movements and adjacent settlements during subsequent excavation.
  • Can be constructed in relatively low headroom and in areas of restricted access.
  • Walls can be quickly formed several hundred feet deep and through rock, with great control over geometry and continuity.
  • Final composition of wall can vary to meet specific site requirements, e.g., plastic concrete for cut-offs.
  • In certain cases, precast panels can be used to provide smooth exposed surfaces.
  • Provide economic solutions in cases where temporary and permanent support can be integrated or redesigned into one retaining structure.