Game Development Reference
In-Depth Information
A wall or ceiling collapse will cause more serious injuries to anyone in the way of the falling
debris. If a building collapses, most of the people inside the building will be killed.
Even if they are not struck by flying debris or crushed under a collapsing building, people
can still be wounded by the effects of a blast wave. Without going into too many gory details,
the most serious nondebris injuries caused by explosions involve the lungs, ears, eyeballs, and
skull. As with structural damage, the severity of wounds to people from a blast wave is propor-
tional to the strength of the blast wave. Table 13-2 lists typical overpressures required to cause
certain types of injuries.
1, 3
Table 13-2.
Personal Injury Levels Due to Blast Wave Overpressures
Overpressure (
N
/
m
2
)
Injury Type
7000-14,000
Knocks a person over
35,000
Ruptured eardrums
100,000
Damaged lungs
240,000
Possibly fatal
340,000
50% fatalities
450,000
99% fatalities
It's interesting when comparing the values in Tables 13-1 and 13-2 that people are actually
tougher than buildings when it comes to resisting blast wave overpressures. An overpressure of
40,000
N
/
m
2
will collapse a wood-framed building but will “only” knock down and rupture the
eardrums of a person standing next to the building. Unless a person is standing fairly close to
the point of explosion, the explosion itself won't kill him. Of course, shrapnel or other flying
debris caused by the explosion might kill the person, a collapsing building may fall on him, and
so on.
TNT Explosion Model
To compute the damage caused by a blast wave requires the estimation of the overpressures
generated by the explosion. Earlier in this chapter you learned that TNT is a standard explosive
against which other explosive types are compared. One reason that TNT is a standard is that a
lot of experimental data is available on the overpressures that are generated by the explosion
of a certain amount of TNT. Based on the experimental data, the
TNT explosion model
was
derived, which determines the overpressures generated by a TNT explosion.
The overpressure level of a TNT explosion blast wave is a function of the distance from the
point of explosion and the amount of TNT that is used. The TNT experimental data showed
that TNT overpressure levels could be characterized by a
scaled distance
,
Z
, that is the ratio of
the distance from the point of explosion divided by the cube root of the mass of TNT.
d
m
kg
Z
=
(13.1)
1/3
3
m
