Liquefaction Evaluation of Densified Sand at Approach to Pier 1 on Treasure Island, California, Using SASW Method.
Liquefaction Evaluation of Densified Sand at Approach to
Pier 1 on Treasure Island, California, Using SASW
Andrus, R. D.; Stokoe, K. H., II; Chung, R. M.; Bay, J.
NISTIR 6230; 80 p. October 1998.
Available from: National Technical Information Service
soil liquefaction; soil improvement; building
technology; SASW test; seismic testing; shear wave
velocity; surface waves; sand
Areas of improved and unimproved soil near berthing Pier
1 at Treasure Island, California, were investigated by
the Spectral-Analysis-of-Surface-Waves (SASW) test. The
upper 12 m of sand fill beneath the approach to the pier
had been densified by a vibrating probe technique in
1985. The area of improved soil, which is 23 m wide and
93 m long, performed well during the 1989 Loma Prieta
earthquake (Mw=7.0), while sinkholes, sand boils and
cracks formed in the adjacent unimproved areas. SASW
tests were conducted on a 240-m-long alignment that
extended across the area of improved soil using a
seismic vibrator as the principal source with receiver
spacings from 7.6 m to 76 m. Average shear wave
velocities determined for the densified and undensified
sand fill below the water table were 192 m/s and 167
m/s, respectively. Two simplified analytical procedures
based on shear wave velocity correctly predict no
liquefaction for the densified sand, and marginal
liquefaction for the undensified sand. Although less
conservative, liquefaction assessment procedures based
on the SPT and CPT provide similar predictions.