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Liquefaction Resistance Based on Shear Wave Velocity.


pdf icon Liquefaction Resistance Based on Shear Wave Velocity. (2990 K)
Andrus, R. D.; Stokoe, K. H., II

Evaluation of Liquefaction Resistance of Soils. National Center for Earthquake Engineering Research (NCEER) Workshop. Proceedings. January 5-6, 1996, Salt Lake, UT, Youd, T. L.; Idriss, I. M., Editor(s)(s), 89-128 pp, 1997.

Keywords:

earthquakes; building technology; in situ measurements; seismic testing; shear wave velocity; soil liquefaction

Abstract:

This report reviews the current simplified procedures for evaluating the liquefaction resistance of granular soil deposits using small-strain shear wave velocity. These procedures were developed from analytical studies, laboratory studies, or very limited field performance data. Their accuracy is evaluated through field performance data from 20 earthquakes and in situ shear wave velocity measurements at over 50 different sites (124 test arrays) in soils ranging from sandy gravel with cobbles to profiles including silty clay layers, resulting in a total of 193 liquefaction and non-liquefaction case histories. The current procedures correctly predict high liquefaction potential at many sites where surface manifestations of liquefaction were observed. Revisions and enhancements to the current procedures are proposed using the compiled case history data. The recommended procedure follows the general format of the SPT- and CPT-based procedures. Liquefaction potential boundaries are established by applying a modified relationship between shear wave velocity and cyclic stress ratio for constant average cyclic shear strain suggested by Dobry. These new boundaries, which are simply defined mathematically and easy to implement, corectly predict moderate to high liquefaction potential for more than 95% of the liquefaction case histories. Additional case histories are needed of all types of soils that have and have not liquefied during earthquakes, particularly from deeper deposits (depth > 8 m) and from denser soils (VS > 200 m/s) shaken by stronger ground motions (amax > 0.4 g), to further validate the proposed procedures.