Approximate Conversion Factor

Explosive

by Weight for Pressure

TNT

1

1.11

Nitromethane

1.042

Pentolite

0.3-0.823

ANFO

1.374

C-4

0.7-0.94

Ammonia Dynamite

0.7-0.84

Gelatin Dynamite

0.94

Nitroglycerin Dynamite

1

Hendry and Welch (to be published 1991).

2

Cole (1948).

3

Dependent on percent fuel oil; factors estimated based on energy content taken from Petes, Miller, and McMullan (1983).

4

Estimate based on airblast data and energy content (Swisdak 1975).

θ, a time constant (in sec), is

peak pressures and impulses generated by the pres-

(3)

ence of all four of these wave components is shown

θ

5

6.0 10

in Figures 3 and 4. Upper bound limits of pressure

and impulse can also be approximated by multiplying

the value obtained from Equation 2 by 2.0, and that

obtained from Equation 4 by 2.5 (from Miller,

Strange, and Pinkston 1971). Note that, because of

interest, is

the interaction of the direct wave with the surface

relief wave, actual peak pressures and impulses for

shallow-water explosions can be a factor of 10 less

than those given by Equations 2 and 4. Since varia-

and λ is the scaled range (in ft/*W*1/3), where *W *is the

tions in water depth can strongly affect the water

shock levels produced, especially at long ranges from

explosive weight (TNT equivalent (in lb)).

a detonation, it is important to monitor the actual

The water shock impulse at a scaled range of λ is

pressure and impulses generated by the explosive

activities.

(4)

1.46 *W * 1/3(λ)

0.89

be caused by the rapid, repeated collapse and expan-

sion of the explosion gas bubble in deep water. The

peak pressures produced by these pulsations are less

signal will be to shorten abruptly the duration of the

than 20 percent of the direct pulse. However,

pressure history seen at the point of interest. The

because the pulsations are of much longer duration,

effect of the bottom-reflected and bottom-transmitted

their associated impulse can be a factor of 4 larger

waves, for most bottom materials, will be to increase

than the impulse associated with the direct wave

the pressure history duration.

(Cole 1948).

4