The aim of this study is to investigate the variation of sandstone mechanical properties under the condition of spilt after high temperature treatment. We heat-treat the sandstone sample at 400–1 000 ℃ and measure its physical properties. Based on that

we use digital image correlation (DIC) to record and analyze the evolution of strain field

crack generation

propagation and penetration process of sandstone that treated by different temperatures under Brazilian test. The results show that: With the increase of temperature

the mass of sandstone decreases

the volume increases

and the P-wave velocity decreases rapidly. When the temperature is lower than 800 ℃

the tensile strength of heated sandstone shows a downward trend

but the overall decrease is not significant

approximately 10%. The influence of high temperature on the tensile strength of sandstone is much greater than that of the compressive strength. When the temperature exceeds 800 ℃

the tensile strength decreases rapidly because of the increase of cracks inside the sandstone. Therefore

800 ℃ can be regarded as the temperature threshold for the tensile deterioration of sandstone. As the heating temperature increases

the pores and fractures of sandstone keep developing

which reduces the difference of strains between the edge and the center of the Brazilian disk.