分级循环加卸载作用下花岗岩变形破坏研究.

The GAW-2000 microcomputer-controlled electro-hydraulic servo rock single-axis testing machine was used to carry out tie classification cyclic loading and unloading test based on the underground deep granite as the test material. The changed of compressive strength, deformation, failure characteristics, residual strain and elastic modulus trend of the specimens were studied under the same increasing load amplitude. The results shown that the peak strength of the rock sample shown a decreasing trend with the increase of the number of cycles per stage under the action of the uniaxial hierarchical cycle plus unloading test, and the cyclic load stress-strain curve was enveloped by a monotonic load stress-strain curve. Rock sample failure characteristics were mainly shear failure, and the failure cracks were more dispersed with the number of cycles increases. During the loading process of the rock sample, the structure inside the rock mass was continuously adjusted so that the structural surface becomes dense and the fissure is more closed. There was a lag phenomenon in the rebound deformation during unloading, and the load start point does not coincide with the unload end point. There were similar features of elastic strain and residual strain on axial and circumferential with the number of cycles changed. Elastic modulus curve of the rock sample changes alternately in a "wavy" pattern. The research results can provide theoretical basis for the gradual rock failure process of underground engineering under action of circulating loads. [ABSTRACT FROM AUTHOR]