Dynamic Load Transfer in Virgin and Damaged Granular Rock Media

Abstract

An experimental investigation is conducted to study dynamic load transfer in granular rock media. The granular rock media is modeled as a one‐dimensional chain of disks fabricated from four different types of white Vermont marble. The study focuses on the effect of microstructure on transient pulse propagation. The transient pulse is generated by exploding a small amount of lead azide charge on top of the rock disk assembly. During wave propagation dynamic contact strains are recorded using electrical resistance strain gages. The location of the strain gages is chosen such that the averaging effects are minimized. This information is used to calculate wave velocity and attenuation as a function of the cumulative damage in the disk assembly. The results indicate a considerable influence of the microstructure and prior loading history on the wave propagation process. A correlation exists between the stress wave velocity and the microstructure of the rock material. Also the wave velocity increases initially and then decreases with repeated explosive loading.