THE UTILIZATION OF EXPLOSIVE LOADING AS A NONDESTRUCTIVE EVALUATION TOOL IN GEOLOGIC MATERIALS

This paper describes the use of a small explosive charge to evaluate geologic material in a non-destructive manner. One-dimensional computations have been performed using the Lagrangian finite difference code WONDY to investigate the effects that open joints and weak layers of unconsolidated material have on the propagation of stress waves resulting from the detonation of an explosive charge. Data from testing conducted by others in models or in full scale in a number of different materials have been collected and examined. Several findings of importance were noted. The computational results indicate that the characteristics of a stress pulse after passing through an open joint are significantly different from those of a stress pulse that has passed through a weak layer. The examination of data from various explosive tests in different media has yielded a way of determining the type of material that the stress pulse has passed through. These preliminary results indicate that it is theoretically possible to excite a geologic medium with a small explosive pulse and determine the type of rock and the extent to which it contains either open joints or weak layers of unconsolidated material.