Design, Construction, and Performance of a Sensitive Braced Excavation in Boston Blue Clay-Video

Video Transcription

Video Summary

A 14-story building with three basement parking levels was constructed in Boston’s Fenway neighborhood, next to historic buildings and MBTA Green Line tracks. The site’s challenging conditions included shallow groundwater, compressible fill and organics, and thick Boston blue clay. To limit impacts on adjacent foundations and transit infrastructure, the team designed a three-foot-thick braced slurry wall and excavated in two phases to keep a neighboring loading dock operational.<br /><br />A key innovation was installing three subgrade slurry-wall struts beneath the excavation floor. These stiffened the wall toes, reduced predicted adjacent-building settlements by roughly half, and eliminated the need for a third level of cross-lot bracing during parts of construction. Extensive monitoring showed the system performed well: building settlements were reduced at strut locations, and MBTA track movements remained within strict project limits. The presentation highlighted the coordination among the owner, design team, contractors, and transit agency that enabled the complex project.

Keywords

Boston

Fenway

slurry wall

subgrade struts

excavation support

ground settlement