Table 2 Precursor point information of instability failure.

From: Macro-micro fracture mechanism and acoustic emission characteristics of brittle rock induced by loading rate effect

Ra

(mm/s)

Cumulative AE events

Cumulative AE energy

AE b-values

AEc−events104

t(s)

σ(MPa)

AEc−energy105(mv·s)

t(s)

σ(MPa)

AE-b

t(s)

σ(MPa)

0.002

8.85

657.93

92.32%σc

4.34

655.54

91.53%σc

1.0852

665.88

92.36%σc

0.004

15.09

600.81

93.76%σc

7.62

583.66

95.64%σc

1.0824

601.96

94.76%σc

0.006

50.99

463.06

94.93%σc

28.11

457.41

95.07%σc

1.1049

458.80

96.85%σc

0.008

83.44

425.39

96.16%σc

38.91

420.19

96.37%σc

1.1247

430.26

97.42%σc