The dynamic mechanical behaviour and characteristics of rocks have been investigated using different techniques. One of the commonly used technique is the Split Hopkinson Pressure Bar technique. However, the measured responses are inferred from the strain gauges attached to intermittent and transmitting bars rather than directly from samples. The authors devised a new experimental apparatus to investigate the behaviour of rocks under shock waves. The device may be fundamentally categorized as the drop-weight apparatus and it is possible to evaluate the mechanical behaviour and characteristics of rocks subjected to shock waves during pre-failure as well as post-failure stages. The rocks tested are tuff, limetsone, granite, marble, gneiss, porphyrite, ranging from soft rocks to hard rocks. The testing conditions correspond to uniaxial compression test and Brazilian tensile test. The nominal impact velocity can be easily adjusted and it can be easily correlated with the measured responses and dynamic mechanical properties. The authors present the outcomes of this experimental study and discuss their implications in the field of rock dynamics.
The dynamic mechanical behaviour and characteristics of rocks have been investigated using different techniques in relation to evaluate the engineering structures by dynamic loads such as those resulting from the impact of missiles or meteorites, One of the most commonly used techniques is the Split Hopkinson Pressure Bar technique, which was originally developed Hopkinson in 1914 to measure stress pulse propagation in a metal bar. Kolsky (1949) refined Hopkinson's technique by using two Hopkinson bars in series, now known as the Split-Hopkinson Pressure bar (SHPB), to measure stress and strain. However, the measured responses are inferred from the strain gauges attached to intermittent and transmitting bars. Furthemore, it is difficult to evaluate the post-failure characteristics of rocks.
The authors devised new experimental apparatuses to investigate the behavior of rocks under shock waves. The devices are fundamentally categorized as the drop-weight apparatus, it can be equipped with load-cell, non-contact type laser displacement transducers, accelerometers and infrared thermographic imaging. Therefore, it is possible to evaluate the mechanical behavior and characteristics of rocks subjected to shock waves during pre-failure as well as post-failure stages. The tested rocks are tuff, limestone, granite, marble, gneiss, porphyrite. In other words, rocks tested range from soft rocks to hard rocks. The testing conditions correspond to uniaxial compression test and Brazilian tensile test. Nevertheless, it is possible to do experiments such as punching tests, bending tests. The nominal impact velocity can also be easily adjusted and it can be easily correlated with the measured responses and dynamic mechanical properties. The authors explain the newly developed experimental apparatus and experiments on various rock under shock loads and present the outcomes of this experimental study and discuss their implications in rock dynamics field.
