Rockburst evaluation index considering degree of hazard and possibility of rockburst occurrence based on energy analysis

In response to the issue of existing rockburst evaluation indices could not fully reflect the features of rockburst．Cyclic loading and unloading experiments were carried out with different rates on granite samples from the Gangdese orogenic belt．The response mechanism under cyclic compression was explored，and the energy assignment and evolution were then revealed．Specifically，the explicit expression of elastic energy evolution was deduced．On this basis，an evaluation index that could measure both the degree of hazard and the possibility of rockburst occurrence was proposed，and the corresponding criterion for rockburst degree classification was determined by minimizing the loss function．Results show that the elastic energy Ue varies consistently with the total input energy Uo during the entire compression process，the evolution of proportion of Ue to Uo can be expressed in an exponential function，and Ue becomes dominant after the compaction stage． The product of elastic energy and the ratio of the maximum principal stress to the uniaxial compressive strength (UCS) is developed as the evaluation index of rockburst，applying it to evaluate the rockburst intensity of tunnel，and the evaluation effect was compared with the actual rockburst situation，thus verifying the reliability． © 2023 Huazhong University of Science and Technology. All rights reserved.