Pipe struts, pin piles, and external wales along south wall, looking west.
Pipe struts, pin piles, and external wale along south wall, looking east.
Aerial view of braced excavation.
Slurry wall installation using hydromill, by client Trevi Icos.
Fully excavated site during mass excavation, looking east.
Foundation Medicine Tower at 400 Summer Street
Comprehensive support-of-excavation design for a cutting-edge Boston high-rise.
In 2019, biotechnology company Foundation Medicine announced plans to establish a new headquarters at 400 Summer Street in the heart of Boston’s Seaport District. The 16-story tower would feature space for offices and state-of-the-art labs, four levels of below-grade parking, and 30,000 square feet of ground-level retail and restaurant space surrounding a tiered public plaza called The Summer Steps. The project was part of the city’s 33-acre Boston Seaport development project, an effort to revitalize the neighborhood while expanding and connecting public spaces from Summer to Congress Street.
GeoEngineers provided support-of-excavation (SOE) services for this cutting-edge development project, including geo-structural design, finite element modeling (FEM), and a global stability analysis.
Approach
- SOE Design: GeoEngineers designed a 758-foot-deep slurry wall to provide temporary structural support during excavation, including bracing layout and connection design. The team performed traditional force and moment balance analysis to determine the maximum loading on the SOE structure.
- Numerical Analysis (FEM): The Fort Point Channel Tunnel was just a few feet from the southeast corner of the project site, so GeoEngineers’ Construction Design Team also performed a soil-structure analysis using finite element modeling (FEM) to determine what impact, if any, the excavation and temporary structural support would have. The team used PLAXIS V9 to calculate loading conditions using a performance-based engineering approach. Compared to traditional limit equilibrium analyses, which result in a factor of safety (FOS) of a shoring wall against failure, PLAXIS calculated site-specific shoring wall forces and displacements directly as the excavation was completed.
- Global Stability Analysis: GeoEngineers also calculated a global factor of safety for critical stages of the shoring design using several programs and analysis methods, then compared results before making geo-structural recommendations.
Results
The Foundation Health headquarters at 400 Summer Street is a marquee addition to Boston’s rapidly growing life science and technology sector, and its innovative design and civic features will benefit the community for many years to come. GeoEngineers is proud to have delivered efficient and safe support of excavation designs for this fast-paced and challenging project.
