PENETRATION INTO DRY POROUS ROCK

Studies on projectile penetration into geological targets usually focus on the prediction and measurement of penetration depth or deceleration history. Theoretical models use solution techniques that may be grouped into three main categories: empirical equations fit to test data; models that approximate the target response by one-dimensional motion using cavity-expansion methods; and wave-code analyses. Author developed closed-form solutions for forces on projectiles that penetrated geological targets. Constitutive target description consisted of a linear hydrostat and a Mohr-Coulomb failure-criterion with a tension cutoff. Predictions from the model were in reasonably good agreement with deceleration data from full-scale field-tests into dry, tuff targets.