CALCULATION OF EXPLOSION-PRODUCED CRATERS
This study develops a simple, two-dimensional, numerical-physical model of cratering physics for highexplosive sources in alluvium during the gas acceleration phase of excavation. The model requires knowledge of the earth's free-surface topography and motion at the time the gas acceleration begins (t/sub G/), and the cavity pressure and volume. At t/sub G/, the overburden material between the cavity and the free surface is assumed to be a homogeneous, incompressible, viscous fluid. Initially (e.g., at t/sub G/) the cavity is approximated by two hemispheres: (a) the radius of the lower hemisphere is calculated by a onedimensional, hydrodynamic, plastic-elastic model, and (b) the radius of the upper hemisphere is calculated from mass conservation of the overburden material, The upper hemispheric surface is subdivided into elemental surface areas, and mass zones are defined which subtend these elemental surface areas. By applying Newton's second law with a Newtonian friction (calibrated on the Scooter event) to each mass element, and by assuming that the cavity gas behaves adiabatically, the cavity evolution, mound development, and the formation of the lip through up-thrust are numerically simulated. With the development of a calibrated, numerical simulation model of excavation processes during the gas acceleration phase, the capability of the model to estimate crater radii and depth for 1/2-kt, high-explosive (H. E.) sources at various emplacement depths is explored. Assuming a reasonable angle of repose for alluvium, 45 deg , crater radii for scaled depths of burst from about 10 to 65 m are predicted. These estimated crater radii compare very favorably with the observed crater radii (Nordyke, 1961) for H.E. in alluvium. Further, the crater depths, for certain types of craters, are also reasonably predicted. The unsolved problems requiring solution for the developraent of a predictive model for cratering with nuclear explosives are discussed. (auth)
- Research Organization:
- California. Univ., Livermore. Lawrence Radiation Lab.
- DOE Contract Number:
- W-7405-ENG-48
- NSA Number:
- NSA-18-020123
- OSTI ID:
- 4030070
- Report Number(s):
- UCRL-7738; CONF-470-3
- Resource Relation:
- Other Information: From 3rd Plowshare Symposium on Engineering with Nuclear Explosives, Davis, Calif., Apr. 1964. Orig. Receipt Date: 31-DEC-64
- Country of Publication:
- United States
- Language:
- English
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