Investigation on the Ground Pressure Induced by Hard Roof Fracturing at Different Layers during Extra Thick Coal Seam Mining

Table 4

The calculated elasticity modulus of strain gauges.

No.	Weight (N)	Strain (10^-3)	Elasticity modulus (GPa)
1	32	210	0.121322414
	64.4	412	0.124451178
2	32	230	0.110772639
	64.4	428	0.119798798
3	32	330	0.077205173
	64.4	540	0.09495164
4	32	290	0.087854162
	64.4	690	0.074309979
Avg.			0.101333248