Experimental study on critical collapse of concrete targets subjected to internal explosion

A series of experiments on the buried internal explosion of TNT in finite concrete targets is carried out, in order to study the critical collapse effect on the target's free surface. For a certain thickness of target, its critical collapse under different diameters and burial depths of explosive charge is obtained by changing the amount of charge. The experiment results show that the critical collapse thickness increases with the amount or length-to-diameter ratio of explosive charge for a certain diameter and density of the explosive charge, but the increase tendency becomes slower and slower; for the same charge density and length, the critical collapse thickness increases with the charge diameter. It is found that the critical collapse thickness of a concrete target depends on both the charge amount and length-to-diameter ratio, and the explosive charge can be regarded as spherical one approximately if the length-to-diameter ratio is less than two.