Rock bending creep and disturbance effects

The bending creep and its disturbance effects of red sandstone rock beam and oil shale rock beam were studied by adopting the self-developed gravitation level style rock creep test machine and bending creep test system, and the constitutive equations were established. It is found that fracture morphology of rock beams under no disturbance load is regular, cracking position of fractures is on part of loading concentration, the crack starts from a neutral plane. However, fracture morphology of rock beams under disturbance load is irregular, cracking position of fractures deviates from a neutral plane. Delayed instability of rock beam occurs for some time under constant disturbance load. When disturbance load is beyond a certain range, suddenly instability of occurs rock beam in a certain time. The results show that there is a guiding significance for creep stability in the geotechnical engineering fields.