Temperature effects on dynamic compressive behavior of siliceous sandstone

This paper studies the dynamic mechanical characteristics of siliceous sandstone (SS) after elevated temperature treatment and discusses the damage mechanism of structure thermal stress on rock. Firstly, the dynamic compression tests of SS under room temperature (25 °C) and different high temperatures (200, 400, 600, and 800 °C) were carried out using the split Hopkinson pressure bar (SHPB). The rock dynamic curves of stress-strain were obtained, and the variation of the strength, peak strain, and dynamic elastic modulus with strain rate and temperature were discussed. Secondly, the scanning electron microscope (SEM) technique was adopted to determine the change of the rock micro-structure as temperature increases, and the mechanism of thermal damage was analyzed. The results show that the SS is sensitive to temperature, and 200 °C and 600 °C are distinct turning points of mechanical properties. At room temperature to 200 °C, the strength increases slightly, decreases from 200 to 600 °C, and then decreases rapidly; the peak strain decreases first and then increases; the strain rate effect of the dynamic elastic modulus of rock at different temperatures is not obvious, indicating that the rock dynamic elastic modulus is a material property, independent of loading rate. The SEM photographs of rock surface after high temperature show that the internal structure of rock affected by temperature is obvious. Significant changes appear at 400 °C, inconsistent with the inflection point of mechanical properties.