### ASA 130th Meeting - St. Louis, MO - 1995 Nov 27 .. Dec 01

## 1aPA5. Underwater explosion shock wave due to a buried charge.

**Alan Powell
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*Dept. of Mech. Eng., Univ. of Houston, TX 77204-4792
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The explosive removal of off-shore oil platform structures has an
environmental impact on marine life because of the shock waves from the buried
charges. For an in-water detonation the similarity parameter (W[sup 1/3]/R) is
well known (W= charge weight, R=radius to observation point), with peak pressure
p[inf max]= const.x(W[sup 1/3]/R)[sup (alpha)], (alpha)=attenuation
coeff.(approximately equal to)1.13 (Arons, 1954). Combining the similarity
method with ray theory gives, for a point distance a above the bottom due to a
charge buried distance b below it, p[inf max]=const.x(W[sup 1/3]/R)[sup (cursive
beta)]{(a+b)/b}[sup (cursive beta)-(alpha)] with (cursive beta)=bottom
attenuation coeff. Now p[inf max] is a function only of (W[sup 1/3]/R) only on
horizontal planes (a+b)/b= const.; moreover for given R, the pressure increases
with height a above the bottom. Full-scale measurements by Connor (1990) confirm
these findings, also yielding (cursive beta)(approximately equal to)1.99. The
pressure now depends more acutely on charge weight, p[inf max]~W[sup 2/3]; but
more weakly on burial depth than p[inf max]~1/b[sup 2.6] as sometimes assumed,
e.g., in deep water a&R>>b, p[inf max]~1/b[sup 0.86]. Constant peak pressure
contours follow R=const.xcos[sup ((cursive beta)-(alpha))/(alpha)](theta),
(theta)=angle to vertical.