Influence of specimen size and formation genesis on the dynamic mechanical behavior of rock types using SHPB

This study presents a comprehensive investigation into the dynamic compressive behavior of ten distinct rock types using a Split Hopkinson Pressure Bar system. The selected rocks represent igneous, sedimentary, and metamorphic origins and are sourced from six geotechnically significant sites across India, each designated as a project of national importance. To establish the fundamental characteristics of the materials, an extensive series of petrological, physical, and static mechanical tests were first conducted. Cylindrical specimens of varying sizes were subsequently prepared to evaluate the influence of strain rate and specimen geometry on dynamic response parameters, including peak compressive strength, dynamic elastic modulus, and peak strain. The experimental data analysis reveals significant variations in mechanical response as a function of rock type and specimen dimensions under high strain-rate loading. A nonlinear regression model is proposed to correlate elastic parameters obtained under static and dynamic loading conditions. Furthermore, the study demonstrates the practical applicability of dynamic test results in estimating rock mass properties. To enhance engineering relevance, all rocks are systematically classified using the Deere-Miller rock mass rating scheme under both static and dynamic loading scenarios. The results contribute valuable insights for the design and analysis of rock structures subjected to dynamic loads such as blasting and seismic events.