Investigation of relationships between soil type and condition and crater size for shallow-buried explosive charges

Abstract

The detonation of near-surface and shallow-buried explosives results in a ground crater that has a size and shape that is directly related to the charge size, charge position, and soil conditions. Several methods are currently available that attempt to predict crater size, that is, apparent depth and diameter of a ground crater, based on direct inputs of key factors such as the soil type, soil conditions, explosive type and mass, and depth of burial of the explosive. Current prediction methodologies are limited, primarily due to the lack of key cratering data in well-controlled and characterized soil backfills consisting of a full range of soil types, water contents, and density conditions. A new cratering database is currently being developed based on craters produced in well-characterized materials representing a significant number of soil types defined by the Unified Soil Classification System. This database is capturing key cratering measurements for charge depth of burials ranging from tangent below the ground surface to a scaled depth of approximately 1.0 ft/lb^1/3. Data collected include water content and density measurements in the as-constructed backfills and measurements of the crater cross-sectional profiles, including the apparent depth and diameter, lip-to-lip diameter, and lip-to-bottom depth. Analyses were conducted on the test data to define key parameters affecting crater size. Based on the results of these analyses, the critical soil parameters affecting crater size were identified.