Research on Structural Characteristics of Dynamic Nuclear Zone in Dynamic System of Coal and Rock

Table 3

Monitoring effect of different types of hole.

Drill number	Borehole diameter (mm)	Maximum strain value (με)	Maximum impact area (radius) (m)
1#	60	143.1	2.0
2#	60
3#	60
4#	65	147.8	2.6
5#	65
6#	65
7#	90	127.6	1.6
8#	90
9#	90