Rockburst in Sandstone Containing Elliptic Holes with Varying Axial Ratios

Table 2

Duration of different periods for specimens with different axis ratios.

No.	Axis ratio	Quiet period (s)	Mean value (s)	Small particle ejection (s)	Mean value (s)	Spalling (s)	Mean value (s)	Rockburst (s)	Mean value (s)
S-1-1	1	230.23	224.48	10.44	8.12	54.21	50.79	0.08	0.11
S-1-2		223.75		6.35		52.51		0.14
S-1-3		219.46		7.58		45.64		0.12
S-1.25-1	1.25	240.59	235.78	7.25	7.18	59.61	56.22	0.12	0.12
S-1.25-2		236.35		8.48		49.84		0.1
S-1.25-3		230.41		5.8		59.21		0.14
S-1.67-1	1.67	255.12	248.25	7.24	9.39	66.13	59.73	0.08	0.12
S-1.67-2		240.43		9.73		55.23		0.14
S-1.67-3		249.21		11.2		57.82		0.14
S-2.5-1	2.5	245.19	250.85	8.36	8.49	65.76	73.43	0.12	0.13
S-2.5-2		260.12		9.65		82.63		0.14
S-2.5-3		247.23		7.45		71.9		0.14