The 1995 Hyogoken-Nanbu earthquake caused widespread liquefaction in Kobe, Japan. At the reclaimed Port Island in Kobe, the observed large-scale liquefaction was documented by acceleration records from a downhole seismic array. The soil stratum response, from the ground surface to a depth of 83 m, was recorded by four accelerometers. The authors used these recorded accelerations to obtain direct estimates of the corresponding seismic shear stress and strain histories within the soil layers, which shed light on (1) the site seismic response during liquefaction and associated loss of soil stiffness at shallow depths near the ground surface; and (2) the virtually linear site response at deeper elevations. Response of the liquefied upper layer is characterized by cycles of large shear strain and very small shear stress. Conversely, the lower layer displayed no sign of stiffness degradation throughout the earthquake. A computational simulation of this case study is undertaken to assess the mechanisms of site amplification and excess pore-pressure buildup. The results of the study suggest that acceleration histories recorded by downhole arrays are a valuable direct source of information on site response during seismic excitation.


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Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: p. 39-49
  • Serial:

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Filing Info

  • Accession Number: 00716444
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Feb 8 1996 12:00AM