Soil Liquefaction Resulting from Blast-Induced Spherical Stress Waves

Abstract : Soil liquefaction resulting from blast-induced spherical stress waves is evaluated analytically and experimentally. An analytical model developed in this research predicts the dynamic and dissipation stages of porewater pressure in saturated sand subjected to the blast-induced spherical stress waves. Experimental test data are from detonations of explosive masses varying from 0. 03 to 7.02 kg in water 1.8 m above a 1.8 m deep by 4.3 m diameter saturated sand sample placed at 84 percent relative density. The sand was saturated to 100 percent and instrumentation included porewater pressure transducers, accelerometers, inductance strain gages, total stress gages, and piezometers. Results of the tests are combined with results from a subsequent series of tests at 50 percent relative density and with charge masses from 0.00044 to 0.0588 kg to form the data base from which the analytical model is substantiated and empirical relations are developed for peak strain, peak porewater pressure, peak particle velocity, and peak residual porewater pressure as functions of scaled distance. Thresholds at which liquefaction is shown to occur are scaled distances 0.6 m/s. Keywords: Soil liquefaction; Blasting; Pore water pressure response; Blast induced liquefaction; Stress wave; Spherical stress wave; Saturated sand; Saturating sand; Explosive testing; Blast testing.