Microsoft Campus Refresh, Redmond, WA (2020)

Shoring System: Permanent VENIS Soil Nailing

Client: Malcolm/DBM, JV

General Contractor: Sellen Construction, HSWCC, and GLY Construction

Shoring Contractor: Malcolm/DBM, JV

Shoring Face Area: 238,000 Square Feet

Wall Depth Range: 27 to 58 feet

Status: Completed 2020

This development was massive, involving a relatively large below-grade parking garage, surrounded by over a dozen new four to five story buildings, most of which are outside of the footprint of the garage, but five are located on top of the garage. The overall garage footprint is quite large, extending roughly 1800 feet from north to south, by about 1600 feet from east to west, and each of the new buildings surrounding the buried garage have two to three-level basements with tunnels and ramps that interface with the garage on every side. The shoring system consisted of a permanent top-down passive soil nailed system, but included full-height vertical elements due to concerns about water bearing advance outwash sands near the bottom of the excavation. The design was extremely complex geometrically, having to account for sequencing of the surrounding basements, tunnels, and ramps, which resulted in soil nails that often were to be subsequently intersected and attached to other walls, the use of tierods, and a variety of interwoven patterns to allow the garage to be constructed and the nails to remain permanent. Movements were less than ½ an inch during construction, and the project was completed ahead of schedule and met all the construction sequencing and loading demands of three major general contractors simultaneously working on portions of the development around the entire garage.