Premiere on Pine is a 40-floor residential high-rise in downtown Seattle, Washington next to the historic Paramount Theater on Pine Street.
The below grade excavation extended 65-70 feet below grade.
Underpinning soldier piles were installed on either side of the adjacent Seattle Convention Center’s drilled shaft foundations to transfer the drilled shaft loads to the soldier piles, given the excavation extended below the base of the drilled shafts.
GeoEngineers to provide geotechnical design and construction observation for excavation, shoring, and the building’s structural mat foundation.
Premiere on Pine
440-foot residential high-rise in downtown Seattle.
In 2011, Holland Construction began development of Premiere on Pine, a residential high-rise in downtown Seattle, Washington. The 440-foot tower boasts 40 floors of upscale apartments and is adjacent to the historic Paramount Theater on Pine Street. Holland hired GeoEngineers to provide geotechnical design and construction observation for excavation, shoring, and the building’s structural mat foundation.
The excavation extended 65-70 feet below grade and excavation support was complex on three of the four sides of the excavation. Two sides of the excavation had deep adjacent structures (the Pine Street light rail tunnel and the 801 Tower basement) offset from the shoring wall. GeoEngineers designed a creative hybrid soldier pile/soil nail/tieback shoring system using numerical modeling to avoid a costly internally braced system on these two sides of the excavation. The third side was located adjacent to the Seattle Convention Center which is supported on drilled shaft foundations that do not extend below the Premiere on Pine bottom of excavation elevation. GeoEngineers collaborated with the structural engineer to design underpinning soldier piles located on either side of the drilled shaft foundations that transferred the drilled shaft loads to the soldier piles by means of a bridge pin assembly.
The tower was designed using performance-based seismic design. GeoEngineers completed a probabilistic seismic hazard analysis to develop the design response spectrum and orthogonal pairs of earthquake acceleration records for use by the structural engineer in 3D dynamic finite element modeling of the structure.
Approach
GeoEngineers played an important construction observation role during the development of Premiere on Pine. Team members carefully observed and validated construction activities, ensuring that they were performed according to our geotechnical recommendations and city building codes. Our observation and testing services included:
- Observing shoring installation
- Observing testing of soil nail and tieback capacity
- Monitoring excavation stability
- Reviewing shoring monitoring data for the shoring system
- Collecting inclinometer data on a weekly basis
- Observation during mat foundation construction to confirm the design foundation bearing capacity, drainage measures, and compaction of structural fill.
- Confirmed tieback de-stressing
- Observation of hardscape subgrades and backfill after the removal of soldier piles
Results
Despite the challenges of a small site, deep excavation and nearby structures, GeoEngineers’ creative design, collaboration with the project team, and ability to model the complex hybrid shoring system resulted in a cost-effective excavation support system without internal bracing. Geotechnical special inspection and monitoring during construction confirmed that system was constructed in accordance with plans and met strict deformation tolerances, and ultimately helped make this large development project a success. Geotechnical special inspection and monitoring during construction confirmed that the system was constructed in accordance with plans and met strict deformation tolerances, and ultimately helped make this large development project a success.
