Liquefaction Resistance Based on Shear Wave Velocity.
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.
Building and Fire Research Laboratory
National Institute of Standards and Technology
Gaithersburg, MD 20899