A Method Based on Elastic Mechanics for Judging Compound Hard Roof and Its Application

Table 2

Rock shear testing data.

Sandstone specimen	Normal stress (MPa)	Shearing strength (MPa)	Mudstone specimen	Normal stress (MPa)	Shearing strength (MPa)
S-1	5	16.04	N-1	1	3.15
S-2	10	17.24	N-2	4	7.36
S-3	15	20.54	N-3	7	9.11
S-4	20	23.23	N-4	10	13.97
S-5	25	27.93	N-5	13	15.62
Average	15	21.00	Average	7	9.84