Risky Business Managed: Up-down Construction in Dense Urban Setting-Video

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Video Summary

The presentation describes the geotechnical design and construction of a 62-story Boston tower with a four-level, 60-foot-deep basement, built just feet from neighboring high-rises. The site straddled Boston’s historic shoreline, with glacial soils and bedrock beneath much of the excavation.<br /><br />To protect adjacent buildings, the team used four-foot-thick slurry walls near the most sensitive neighbors and top-down construction, with permanent floor slabs bracing the walls. They also carefully sequenced wall panels, installed a reinforced pressure slab to limit groundwater-related settlement, and used extensive modeling and instrumentation to predict and monitor impacts.<br /><br />A third-party geotechnical peer review helped build confidence among the owner, neighbors, city, and project team, and contributed to design and monitoring improvements. Construction movements remained within agreed limits: nearby buildings settled roughly 0.2–0.3 inches, and groundwater levels recovered after the pressure slab was completed. The project demonstrated the value of detailed analysis, monitoring, communication, and independent review.

Keywords

geotechnical design

slurry walls

top-down construction

deep excavation

Boston tower

groundwater settlement