A waveform modification method for testing dynamic properties of rock under high temperature

In this study, a waveform modification method was proposed using a self-designed heating device combined with the split Hopkinson pressure bar (SHPB) technique for determination of dynamic behaviors of rock at high temperature. Firstly, the temperature gradient distribution on the incident bar was measured according to the variation of elastic modulus of the bar with temperature, and the relationship between the longitudinal wave velocity and temperature of the bar was obtained based on one-dimensional stress wave theory. The incident bar with a temperature gradient was divided into a series of microelements, and then the transmission coefficient of the whole incident bar was obtained. Finally, the stress wave was modified by the transmission coefficient from 25 °C to 600 °C. This method was used to study the dynamic properties of rock at high temperature, which not only preserves a classical SHPB device, but also effectively ensures the accuracy of the experimental results. A dynamic Brazilian disc experiment was carried out to explore the influences of loading rate and temperature on dynamic tensile strength of sandstone at high temperature using the proposed waveform modification method.