Apartment Foundation Repair

Problem:

After an apartment building burned to the ground, there were concerns that the helical piles which had been previously placed for apartment foundation repair may have been compromised by the significant amounts of water used in the firefighting operation.

During the investigation of the original apartment foundation repair helical piles’ integrity, it was discovered that the critical buckling load of the piles was nearly 5 kips less than the working load. While refusal was relatively shallow (20 feet), there were multiple feet of WOH soil, which did not provide adequate lateral support for the lightweight square bar existing piles.

Extensive voids under an adjacent breezeway slab were also discovered, and there were also extensive voids under the footings from the previous underpinning work.

Solution:

Due to the inadequacy of the original helical piles, installation of new, adequately-sized helical piles was the best solution. Concrete Jack, in partnership with our material supplier, Earth Contact Products, designed a round shaft helical pile system which would provide adequate bearing capacity and buckling loads despite the very weak soils. The piles were triple helix (10-12-14) 2 7/8″ round shaft piles.

High density polyurethane foam jacking was proposed for filling voids under the breezeway and footings.

Constraints:

The apartment building was at the top of a steep slope, which significantly constrained access. Time was of the essence, given the need to install the helical piles before the affected walls were reloaded by reconstructing the three story apartment building.

Results:

Concrete Jack foundation repair crew installed 8 ECP helical piles to stabilize the foundation.  After the helical piles were installed, the foundation integrity was restored.  A Concrete Jack foam jacking crew then installed NCFI high density polyurethane to fill voids below the footings and breezeway slab.

This apartment foundation repair project is a great example of how foam jacking and helical piles can be used together for ensuring integrity of foundations.