Retaining Tie Back Wall Stabilization

Cincinnati Ohio High School Retaining Tie Back Wall and Floor Stabilization

Turpin High School was trying to make an addition to its high school gym. There was concern that excavation of soils around the building would undermine the existing slabs and foundations. In order to stabilize the soils, the engineer worked with GWS to design a retaining tie back wall using a high-density polyurethane chemical grout. Once the retaining tie back wall was completed, the general contractor would use the excavation zone to install caissons to support the new addition.

Project Challenges

  • Access through gym over 150’
  • Proposed construction required drilled shafts to be excavated in weak soils
  • Engineer concerned that undermining of adjacent slabs and foundations would occur
  • Injections were made from inside the building to create a tied back soil mass when excavating from outside

Solution

  • Inject URETEK 486Star Polymer through slab and into the soil to create a soil tie back wall capable of retaining soils during drilled shaft excavation
  • Worked with general contractor to determine injection depths based on bottom of drilled shaft elevations

Outcome

  • Work completed in 4 hours
  • Injected to create a free standing soil mass
  • Excavation soil was tied back and successfully underpinned the slab and surrounding footings