The experimental results on dynamic response of granite, limestone, basalt and Moravian graywacke are presented and analyzed in this paper. The rock specimens were loaded dynamically in compression by means of the Hopkinson Split Bar Test (HSBT) with a strain rate of approximately 10³ s⁻¹ and with the stress pulses having different duration times λε (30 + 80) μs. These dynamic results were used to study the amplitude and frequency response which was then related to the fracture damage.

A new interpretation of stress wave propagation during HSBT, described here, made it possible to identify the complex process accompanying impact rock spalling. Special attention is paid to the dynamic strength and its dependence on strain rate, duration time, and specimen length. The results show that fracture damage has a similar influence to permanent deformation of ductile materials. The equation of state describing the mechanical behavior of investigated rocks was suggested for complicated conditions of impact rock spalling.