Laboratory Particle Velocity Experiments on Indiana Limestone and Sierra White Granite.

摘要

Laboratory experiments were performed to determine the influence of freezing on the spherical wave generated by a small spherical explosive charge in rock. The work is relevant to the Soviet nuclear test site in Novaya Zemlya where permafrost conditions exist. The results are also valuable for developing and validating material modeling in continuum mechanics codes used for source coupling calculations. The experiments were performed with cores of well characterized Indiana limestone (porosity 16%) under frozen/dry and frozen/saturated conditions and well characterized Sierra White granite (porosity 0.8%) in a frozen/saturated condition. The spherical waves were determined by particle velocity measurements at several ranges. The effect of freezing was evaluated by comparing these results from our past room temperature experiments with the same rock type. From the particle velocities, we obtained displacements, reduced velocity and displacement potentials, spectra of these quantities, and radiated kinetic energy. The main conclusions are that freezing the dry limestone and saturated granite had no effect on the spherical waves. However, freezing of the saturated limestone had a substantial effect on the spherical waves. These effects included an increase of wave speed and reductions of maximum outward velocity, inward and outward phase durations, and displacements.