Effect of spall on the characteristics of explosive ground motion. Final report 1 may 81-30 apr 82

An empirical technique is developed for predicting the vertical and horizontal extent of spall in soil or rock due to near-surface chemical or nuclear explosions. One-dimensional numerical analyses are presented describing multiple spalls in a tensilely weak, hysteretic material with a free surface. Theoretical analyses of the pore air effect are presented. They show that a fundamental understanding of soil spall requires an effective stress approach.