Rockburst failure characteristics of sandstone under true triaxial double-sided rapid unloading conditions under high pressure

Abstract

To explore the evolution process and failure characteristics of rockburst in rock masses with a double free surface structure, we conducted a comparative study between true triaxial double-face rapid unloading rockburst tests and single-face rapid unloading rockburst tests, using a true triaxial experimental system capable of rapid unloading from multiple faces. The main conclusions are as follows: the maximum ejection velocity of double-free surface rockburst fragments is higher than that of single-free surface rockburst (20 %-40 %), and the rockburst ejection duration is generally longer than that of single-free surface rockburst; the peak stress of double-free surface rockburst is smaller than that of single-free surface rockburst, but there will be a more obvious unloading platform stage during unloading. Compared with single-surface unloading rockburst, double-surface unloading is more likely to cause significant brittle failure and violent rockburst; the AE events of single-free surface rockburst are concentrated near one free surface, while the AE events of double-free surface experiments are distributed near two free surfaces. In the later stage of both rockburst experiments, the number of shear cracks will exceed that of tensile cracks. The extra free surface of double-free surface rockburst will enhance crack extension, especially shear cracks, resulting in more serious rock damage.

Keywords

True triaxial / Double free surface rockburst / Ejection velocity / Acoustic emission / Crack evolution

CRediT authorship contribution statement

Jieyu Li: Writing - original draft, Writing - review & editing, Visualization, Investigation, Data curation. Pengfei Shan: Investigation, Visualization, Validation. Jianning Liu: Conceptualization, Methodology, Supervision, Project administration, Writing - review & editing. Yunpeng Guo: Methodology, Validation, Investigation. Xiaomin Wang: Data curation, Investigation. Zihan Feng: Visualization, Software, Investigation. Chenguang Liu: Investigation, Resources. Chaochao Tian: Validation, Formal analysis. Yuting Mao: Investigation, Data curation.

Declaration of competing interest

The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Zihan Feng is currently employed by Shuanglong Coal Mine, Huangling Mining, Shaanxi Coal Group, Chenguang Liu is currently employed by China Coal Technology Engineering Group Xi'an Research Insititute, and Chaochao Tian is currently employed by Ruineng Coal Mine, Huangling Mining, Shaanxi Coal Group. The other authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the State Key Laboratory for Tunnel Engineering (No. TESKL202424), National Natural Science Foundation of China (Nos. 52404142 and 52304111), and Yulin science and technology plan project of China (No. 2024-CXY-163).

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