Technical Note 3 – Seismic Settlement of Silty Soils

Seismic Settlement of Silty Soils

By Fred Yi, PhD, GE

February, 2014 Modified: July 10, 2015

A case history for a site in the western San Fernando Valley area of Los Angeles was published recently (Lew and Tran, 2012). The soil profile of the Los Angeles site consists mainly of clayey and sandy silt. Lew and Tran (2012) report that the calculated liquefaction-induced seismic settlement using the fines content correction method is almost six times greater than the average of the observed settlement at the Los Angeles site. Using the soil profile provided in Lew and Tran (2012) paper, Yi (2014) found that the correction of liquefaction-induced volumetric strain by a factor of (1-FC/100), where FC is fines content, for fines content higher than 35 percent, gives an estimated liquefaction-induced seismic settlement very close to the observed settlement at the Los Angeles site. GeoSuite© provides options for seismic settlement corrected for fines contents.

SiltCorrOptions

Seismic settlement correction for silty soils

  To be conservative, a correction factor of (1-FC/100)0.75 is recommended. References:

  1. Lew, M. and Tran, L. (2012), Case History of Observed Liquefaction-Induced Settlement versus Predicted Settlement, Proceedings of the 15th World Conference on Earthquake Engineering, Lisbon, Portugal, 2012
  2. CHJ Incorporated, (2014). Update to Recommendations to Comply with the 2013 California Building Code, Proposed East County Detention Center, Southwest of the Intersection of Highway 111 and Oasis Street, Indio, California. Dated August 28, 2013, Job No. 13491-3
  3. Yi, F., 2014, “GeoSuite 2008, version 2.2.0.126 – A Comprehensive Package for Geotechnical and Civil Engineers”, GeoAdvanced, http://geoadvanced.com/