| This study involves seismic tests in blast-liquefied soils that were carried out at four different test sites at Treasure Island in the San Francisco Bay. In these four tests, controlled blasting techniques were used to induce soil liquefaction. The in situ shear wave velocities and P-wave velocities were then monitored using the seismic crosshole method. Within 30–40 seconds after the blast, measurements of the body wave velocities began. This study concludes that blast-induced soil liquefaction reduces the shear wave velocity to 65% of the pre-blast velocity for measurements performed 30–40 seconds after the blast. The final shear wave velocity was 10% to 20% higher for the first three measurements due to the densification effect of blasting. At the first three measurements the pre-blast P-wave velocity was approximately 5200 ft/sec and did not change after blasting. Poisson's ratios, shear wave amplitude ratios, and P-wave amplitude ratios have been calculated and presented for each test site. |
