Research on uniaxial stress compression mechanical properties and uniaxial stress failure mode of pre-cracked rock

Based on the crack initiation, expansion and coalescence of the rock itself under the action of compressive load, it will cause the collapse and instability of the rock mass structure. This paper uses the self-developed stress loading equipment, rock mass tomography scanner and high-speed camera to analyze the sandstone samples. Perform uniaxial compression mechanical properties and compression failure characteristics tests. The results show that the change trend of the axial stress-strain curve of the single pre-cracked sandstone specimen and the complete sample sandstone is approximately the same. The mechanical parameters such as the yield strength, yield strain and elastic modulus of the single-cracked sandstone specimen under uniaxial compression are far lower than the complete sample sandstone specimen. The yield strength of the pre-cracked sandstone specimens increases with the increase of the pre-crack angle. When the porosity of the sandstone specimen remains unchanged, the elastic modulus of a single pre-cracked sandstone specimen is approximately the same, and both are less than the elastic modulus of the complete specimen. There are three typical cracks in the pre-cracked sandstone specimen during uniaxial compression: wing cracks, coplanar secondary cracks and inclined secondary cracks. This paper provides an improvement and supplement to the experimental mechanics performance for the theoretical basis for predicting the collapse and failure of engineering rock mass structures.