The influence of soil and rock properties on the dimensions of explosion produced craters

Abstract

Analysis of data from published cratering experiments shows the effect of soil and rock properties on the apparent dimensions of explosion produced craters. More than 200 cratering tests and related material properties were cataloged. The data consisted of 10 nuclear events whose yields varied from 0.42 to 100 kilotons and about 200 high explosive events who yields varied from 1 to 1 million pounds of TNT. The different test sites included materials for which the density ranged from 60 to 170 pounds/cubic foot. By regression analysis, using bell shaped curves, prediction formulas were developed for the apparent crater radius, depth and volume as a function of charge weight and depth of burst for eight different types of materials. The bell curves were normalized using material properties and prediction equations were generated using all the data. These general equations were then studied to determine the specific effects of the material properties on resultant apparent crater dimensions. Material properties are highly important in determining the size of explosion-produced craters and some of the more important properties are unit weight, degree of saturation, shearing resistance and seismic velocity. Previous investigators have been somewhat negligent in measuring material properties for past cratering experiments and no real analysis data will be made until the variables are either controlled or measured. Material properties which should be measured for future tests should at least include the above properties and if possible the material's energy dissipation and bulking characteristics. Better yet a reasonably simple theory of cratering is needed which will better define the material properties governing cratering mechanics.