Hollow Glass Microspheres Inhibit Blast-Induced Liquefaction
This paper summarizes the results of a controlled series of undrained shock tests conducted on mixtures of Monterey No. 0/30 sand, water, and hollow glass microspheres. Hollow glass microspheres, utilized to entrap gas in the sand, have a collapse strength of about 1700 kPa, are stable over time, and remain passive until a pressure sufficient to collapse them is applied. When subjected to a sub-millisecond compressive stress pulse of about 2300 kPa, peak stress transmission ratio decreased about 50% as the saturation decreased from 100 to 99.5%. Positive residual excess pore pressures (decreases in effective stress) were measured at saturations of 100, 99.9, and 99.8%. Negative residual excess pore pressures (increases in effective stress) were measured at saturations of 99.7, 99.6, and 99.5%. Analysis indicates that no change in residual pore pressure should occur at a saturation of 99.77%. The results indicated that microspheres may be used as a passive measure to inhibit blast-induced liquefaction and for reducing peak blast-induced stress in saturated soils.