Lincoln Square Expansion, Bellevue, WA (2014)

Shoring System: Temporary Soil Nailing with Prestressed Nails at Art Museum, Anchored Piles

Client: GLY Construction Inc.

General Contractor: GLY Construction Inc.

Shoring Contractor: Malcolm Drilling Company Inc.

Shoring Face Area: 112,800 Square Feet

Wall Depth Range: 60 to 81 feet

Status: Completed 2014

The proposed development included the expansion of the existing Lincoln Square hotel, retail, and parking complex toward the south, which involved the construction of two high-rise residential and office towers, as well as several levels of retail and mixed-use space located at grade. Beneath all of the new facilities, a six to seven-level parking structure was built which extends from 60 feet up to 81 feet below existing grade. The proposed parking garage expansion is approximately rectangular in shape, except for a re-entrant corner condition created in the northwest where the existing Bellevue Art Museum (BAM) occupies a 160-ft by 140-ft portion of the site. This existing building with two levels below grade had to be vertically and laterally supported, and held with minimal movement as part of the proposed shoring scheme. While the rest of the site was shored with VENIS-type soil nailing, the system at the BAM included full-depth vertical elements, shotcrete, and prestressed soil nails drilled at 45 degrees into the corner. Also, a combination of soil nailing and anchored piles was utilized in a short section of the north wall in order to accommodate the existing Lincoln Square garage as well as a future tunnel connector. Movements were not detected at the BAM, and the rest of the shoring walls experienced about a 1/2 inch of movement.