Pile Foundations - Shoring Engineers | Established 1977

Concrete underpinning was preformed using alternate pit sequence.  The underpinning was constructed using two lifts due to the difficulty of excavating large boulders and cobbles which were encountered in the sheeted pits.  Sheeted pits were hand excavated to 20 feet deep for the first lift.  Reinforcing steel was installed and concrete was poured. 

Steel plates, wedges and drypack were used to transfer building loads onto underpinning.  Earth tiebacks of 100 kip capacity were drilled tested and locked-off to provide lateral support of the underpinning as the excavation proceded to the bottom of the first lift of underpinning.  The entire underpinning and tieback procedure was repeated to advance the underpinning to the required subgradeelevation.


New York Hospital - Queens Underground Parking Structure

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Macro Enterprises completed the design and installation of a sheeting and underpinning system for a 35 foot deep excavation for a new underground parking garage. 

The Sheeting system consisted of steel soldier piles, timber lagging and earth tiebacks.  Soldier piles were installedwithout impact noise or vibrations by advancing a continuous flight hollow shaft auger into the ground for the full length of the soldier pile.  A self-hardening slurry was pumped through the hollow shaft to hold the hole open while the auger was being withdrawn.  The soldier pile was lowered into the slurried hole.  After the slurry hardened, timber lagging and grouted earth tie-backs were installed to resist the lateral earth pressures as the excavation proceeded.

Installing reinforcing in underpinning pits.

Drilling tie-backs to support the underpinning.

Tie-backs and walers at soldier beam wall.

Chipping of hardened drilling slurry for installation of lagging boards.