A History of Research and a Review of Recent Developments

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Pressure measurement and blast simulation
and reaches a maximum negative pressure when Chamber 2 is exhausted. An
advantage of this system is that for calibration purposes the specimen under
test can be loaded statically by using Chamber 2 only and filling it slowly with
compressed air. Further, Chamber 2 acting alone can be used to simulate a
detonation explosion by suddenly filling it with compressed air. An instantaneous
pressure rise cannot be achieved of course, but a rise of 3 to 5 msec is acceptable
if the test specimen has a long duration natural period of oscillation. The rate of
decay of pressure after the peak has been reached can be controlled by the size
of the opening in Chamber 2. A small opening gives a pressure-time curve shape
not unlike that from a nuclear weapon, and a large opening gives a relationship
similar to that of a conventional explosion.
6.3 SIMULATION OF LOADS ON UNDERGROUND STRUCTURES
The application of shock loads to the surface of soils under which protective
military structures have been buried became important in the 1960s, when
the moratorium on full-scale nuclear weapon tests meant that other means of
accumulating experimental data had to be found. The problem was attacked
in several ways and on several scales. Some of the large air-blast simulators
Figure 6.8 Construction and method of operation of a deflagration simulator (from
Hoffman and Behrens, ref. 6.36).