Foundation Settlement and Tilt of Millennium Tower in San Francisco, California

The Millennium Tower is a 58-story reinforced concrete building that was constructed in San Francisco, California, between 2005 and 2009. founded on an embedded pile-supported mat with pile tips bearing dense marine deposits overlie overconsolidated clay layer known locally as Old Bay clay. This experienced stress increases from self-weight multiple episodes of dewatering 2006 2018 at the site neighboring sites, including one sustained for 6 years. Settlements foundation have been measured since 2006, lateral deflections inferred data show during “loading” (from increase or dewatering), settlements initially accelerated then gradually slowed over time, expected consolidation principles. Similarly, tilt) (1) following construction activities adjacent sites (dewatering excavation); (2) oriented toward excavations, which various times occurred to project south, north, east, west site. An objective this paper describe case history, geotechnical conditions results monitoring program tracked settlements, tilt, groundwater levels site, ground inclinations time. We also evaluate soil deformation mechanisms likely produced movements. find settlement amounts time variations are well captured by one-dimensional three-dimensional analyses volume change other soils primary secondary compression, provided level accounted for. Three-dimensional capture deflections, were caused shear deformations soils, latter having affected unloading excavations.