Page 265 - Dynamic Loading and Design of Structures
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Figure 6.4 Overpressure and dynamic pressure versus range from a I-MT explosion (Biggs, 1964).
6.2.3 Comparing explosives
The TNT equivalence of an explosive is the weight of TNT which produces a pressure wave
in air with one of its characteristics equal to that of the shock wave produced by the explosive
at the same distance. The peak pressure or impulse define the shock wave but its shape is also
distinguished by the rise time, decay time, positive phase duration or negative phase duration.
All of these characteristics vary with the distance the shock wave has travelled in air.
The equivalent weight of TNT is based on peak pressure or impulse and is larger for peak
pressure than for impulse.
Explosives differ in the rate at which they detonate and the heat produced and these
influence the characteristics of the shock wave in air.
6.2.4 Shock wave sealing
The parameters of the shock wave from one explosive charge can be related to the parameters
of the shock wave from a similar shaped charge of the same explosive, but of a different size.
(1) Principle of similitude
If for two charges of the same shape and the same explosive all the dimensions of the
