Failure mechanisms and precursory characteristics of deep buried granite in a tunnel in Southwest China [西南地区某深埋隧道花岗岩破坏机制与前兆特征研究]

作者：Chen B.; Wei F.; Wang R.; Li T.; Zhu X.; Wang X.

来源：Chinese Journal of Rock Mechanics and Engineering, 2020, 39(3): 469-479.

DOI：10.13722/j.cnki.jrme.2019.1151

• Acoustic emission
• Deep buried granite
• Failure mechanism
• Failure mode
• Precursory characteristics
• Rock mechanics

In this study, a uniaxial compression with acoustic emission, elastic wave velocity and SEM scanning test was conducted to study the failure mode, mechanism and precursory characteristics of deep buried granite in Southwest China. It is found that the granite in the tunnel has obvious “time-delayed type” and “immediate type” failure characteristics and the “time-delayed type” failure also has obvious “intermittent”characteristics. The sound, phenomenon, incubation time and duration of “time-delayed type”failure are obviously different from those of “immediate type”failure. The “time-delayed type”is dominated by shear failure, while the “immediate type”is dominated by tension-shear mixed failure. Before failure, lg(AF/RA)(AF/RA is characteristic parameters of acoustic emission that can represent failure types) of the “time-delayed type”increases obviously, while the change of the “immediate type” is not obvious. The wave velocity of the two types before failure decreases obviously, but compared to the “immediate type”, the precursor of the “time-delayed type” failure appears earlier and the amplitude of the decrease is larger. Besides, the main frequency bandwidth of the”time-delayed type” is larger while the mean value of main frequency of the”time-delayed type” is lower. Before the “time-delayed type” failure, the dominant frequency distribution between the bands of 170-260 kHz is strengthened with a trend of “nucleation”, but the precursory feature of “immediate type” failure is not obvious. The research results are of great significance to the recognition of occurrence mechanism, early warning and prevention of granite rockburst in Southwest China.

• 单位
  岩土力学与工程国家重点实验室; 中国科学院大学