Sequential analysis of ground movements at three deep excavation sites with mixed ground profiles

Min Woo Seo, Scott Michael Olson, Ku Seung Yang, Myoung Mo Kim

Research output: Contribution to journalArticlepeer-review

Abstract

Field measurements of settlement and lateral deformation obtained from three deep excavation sites constructed in mixed ground profiles are presented and analyzed. Settlement measurements were obtained throughout the construction process, categorized in three stages as: (1) preexcavation (i.e., preliminary site work and support wall installation); (2) main excavation and bracing/anchor installation; and (3) postexcavation (i.e., removal of bracing as basement construction proceeds). Maximum preexcavation stage settlements of 0.03%Hw to 0.06%Hw (where Hw=wall or trench depth) were measured at two sites, with the maximum settlements occurring adjacent to the wall during its installation. Maximum ground surface settlements during the main excavation stage ranged from about 0.15%He to 0.30%He (where He=final excavation depth) and the distribution of ground settlement extended to a distance of 1.5He to 2.0He from the wall. Maximum settlements occurred at distances of about 0.3He to 0.5He from the wall at two sites where the wall consisted of concrete cast in situ (concrete diaphragm and concrete secant pile walls), creating a significant reverse curvature in the settlement distribution. The maximum postexcavation stage settlements ranged from 0.07%He to 0.10%He for the three sites, representing roughly 10 to 60% increases in settlement over the main excavation settlements, depending greatly on the specific support removal methods as well as the basement floor construction details employed at an individual site. Lateral deflections during the main excavation stage were consistent with trends reported in the literature, ranging from 0.12%He to 0.23%He, while lateral movement during postexcavation stage ranged from 0.03%He to 0.09%He. Finally, the settlements measured during the main and postexcavation stages are related to the support system stiffness.

Original languageEnglish (US)
Article number002005QGT
Pages (from-to)656-668
Number of pages13
JournalJournal of Geotechnical and Geoenvironmental Engineering
Volume136
Issue number5
DOIs
StatePublished - May 2010

Keywords

  • Anchors
  • Bedrock
  • Bracing
  • Diaphragm wall
  • Excavation
  • Lateral displacement
  • Residual soils
  • Settlement

ASJC Scopus subject areas

  • Environmental Science(all)
  • Geotechnical Engineering and Engineering Geology

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