Stress and displacement effects due to subsurface barriers laid under cement concrete runways

The introduction of a polystyrene subsurface barrier layer directly beneath a cement concrete runway will reduce the ground shock effects and runway cracking due to an underground explosion. By modelling the underground void (camouflet) formed by the explosion, and applying a uniform pressure load to the runway, it was found that the polystyrene barrier increased runway deflection, with the increase being less over the camouflet than over the undisturbed subgrade. Further, by comparing the results of the computer models both with and without the polystyrene layer, it was shown that the polystyrene layer reduced stresses for 72% of the load case/stress position combinations considered, and increased it for the remaining 28%. A means of identifying the location of a camouflet is described.