Olive 8 Innovative Shoring Design
GeoEngineers’ unconventional shoring system yields $1.5 million in construction savings
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GeoEngineers provided geotechnical engineering services and seismic-design recommendations for this 39-story high rise
Expertise
  • Geotechnical

Market
  • Development

Location
  • Seattle, Washington

Overview

Overcoming challenging design constraints, GeoEngineers designed and modeled a unique combined shoring system to significantly reduce costs for a 39-story mixed use high-rise in downtown Seattle.

Approach

Removing and replacing the alley soils was impossible due to the presence of sensitive downtown electric and communication utilities, and with an adjacent 50-foot-deep basement wall across the alley, the only typically available alternative was expensive internal bracing. GeoEngineers challenged conventional thinking by:

  • Designing a shoring system consisting of soldier piles with soil nails in the upper portion of the excavation and tiebacks below the adjacent building in the lower portion.
  • Modeling the wall performance using a 2-D finite element model carefully calibrated to specific site conditions.
  • Seismic design of this tall building was also a challenge. GeoEngineers worked closely with the structural engineer to develop a series of site-specific response spectra and acceleration records based on documented past experience for input into their 3-D dynamic model.

Awards


  • ACEC-Washington Engineering Excellence Award, 2007

  • ASCE-Outstanding Project Award, 2006

Results

The high-rise, consisting of 170 upscale condominiums atop a 343-room luxury hotel, was completed in 2007. The owner estimated that the innovative shoring approach saved more than $1.5 million.