Blast-Induced Pore Pressure and Liquefaction of Saturated Sand

AbstractThis paper presents results from field tests using explosive generated spherical stress waves to induce residual excess pore pressure and liquefaction in large saturated sand specimens. Twenty-two single spherically shaped explosive charges ranging from 0.00045 to 7.02 kg were suspended and detonated in water located over saturated sand. Little or no residual pore pressure was induced in loose, dense, and very-dense saturated specimens at peak radial particle velocity less than approximately 0.07 m/s (peak shear strain less than approximately 0.005% at peak stress; late-time shear strain less than approximately 0.015% at peak displacement). Liquefaction was approached when peak radial particle velocities exceeded 0.49,0.52, and 0.71 m/s (peak shear strains exceeded 0.03, 0.03, and 0.04% at peak stress; late-time shear strains exceeded 0.09, 0.09, and 0.12% at peak displacement) in the loose, dense, and very-dense specimens, respectively. Peak radial particle velocity and peak strain required to induce a given pore pressure ratio increased with increasing relative density and effective stress. Empirical relationships developed are for single charge detonations.