Delineation of Densified Sand at Treasure Island by SASW Testing.
Delineation of Densified Sand at Treasure Island by SASW
Andrus, R. D.; Chung, R. M.; Stokoe, K. H., II; Bay, J.
Geotechnical Site Characterization. Site
Characterization - ISC'98, 1st International Conference.
Volume 1. April 19-22, 1998, Atlanta, GA, A.A. Balkema,
Rotterdam, Netherlands, Robertson, P. K.; Mayne, P. W.,
Editor(s)(s), 459-464 pp, 1998.
building technology; earthquakes; liquefaction; seismic
testing; shear wave velocity; soil improvement; 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 performed well during
the 1989 Loma Prieta earthquake, while sinkholes, sand
boils and cracks formed in the adjacent unimproved
areas. The SASW tests were conducted on a 240 m-long
alignment that extended across the area of improved
soil. 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 liquefaction assessment procedures based on
shear wave velocity correctly predicted no liquefaction
for the densified sand, and marginal liquefaction for
the undensified sand.