Effects of water content and temperature on creep properties of frozen red sandstone: an experimental study

To investigate the long-term stability of geotechnical engineering in cold regions, a low-temperature triaxial creep test device was developed for monitoring the rock resistivity during rock creep tests. The creep mechanical properties of red sandstone under different temperature and water content conditions were analyzed. Additionally, the resistivity data were analyzed to determine the state of the internal fractures of the rock. Nuclear magnetic resonance technology was used to analyze the influence mechanism of pore water in frozen red sandstone on the creep characteristics. Finally, with consideration of the resistivity, a mesoscopic analysis of the conductivity of frozen rock at negative temperatures was performed. The results indicated that at room temperature (20 °C), the initial instantaneous elastic strain of the red sandstone samples increased linearly with an increase in the water content, but the failure stress and long-term strength both decreased with the increasing water content. In contrast, at negative temperatures (− 5, − 10, and − 20 °C), the initial instantaneous elastic strains of the samples decreased linearly with the increase in the water content, but the failure stress and long-term strength both increased with the increase in the water content. Thus, water reduces the long-term strength of rocks at room temperature and enhances the long-term strength of rocks at negative temperatures.