Effect of porosity on the cratering efficiency of underground peaceful nuclear explosions in a shale medium

Abstract

The effect of porosity on the cratering efficiency as measured by the kinetic energy imparted by a peaceful nuclear explosion to a shale medium has been evaluated, using a spherical symmetric rock mechanics computer code. A model using the measured material properties of the rock medium has been developed to represent the effect of porosity on the shear strength and compressibility (coupled parameters) of the rock. The calculated spall velocities, peak pressures and kinetic energies show that the cratering efficiency of this shale is first enhanced with increase in porosity and then degraded. This is due to the fact that at low porosities, the strength effects are more significant and at high porosities, the effects due to compressibility are more dominant.