Laboratory Investigation of Expansion, Venting, and Shock Attenuation in the MX Trench

An experimental program using 1/26-scale models of a buried concrete trench was conducted to study the dynamics of expansion and venting caused by an airblast propagating down the trench, and to study the effects of the expansion and venting on the attenuation of the airblast. The trench models were made of steel fiber-reinforced concrete and were buried in sand. The airblast was produced with an explosively driven shock tube. Expansion and venting dynamics of short trench sections were studied for flat-topped pressure pulses ranging from 700 psi to 2600 psi. Radial expansion histories and vent-times were recorded. Shock attenuation was studied with 60-ft-long trenches in which the peak pressure of an exponential waveform decreased from 4000 psi to 300 psi as the shock propagated the length of the trench. The effects of expansion were isolated by comparing the attenuation in a concrete trench to that in a steel trench. Expansion reduced the peak pressure slightly at distances greater than 40 ft. The data were used to validate computer models for shock attenuation in the MX trench. Paper Submitted for Presentation at the American Society of Civil Engineers, National Spring Convention, Las Vegas, NV., Apr 82. See also AD-A130 314.