Application of Presplitting Blasting Technology in Surrounding Rock Control of Gob-Side Entry Retaining with Hard Roof: A Case Study

Table 1

Experimental mechanical parameters of each rock stratum.

Sample name	Sample number	Uniaxial compressive strength (MPa)	Uniaxial tensile strength (MPa)	Cohesion (MPa)	Internal friction angle (°)
Main roof	1-1-1	65.42	5.86	7.72	45
	1-1-2	63.45	5.96	7.86	42
	1-1-3	67.30	5.42	7.95	43
Immediate roof	2-1-1	33.56	4.49	2.59	40
	2-1-2	30.21	4.51	2.46	36
	2-1-3	36.98	4.66	2.50	38
7# coal	3-1-1	8.45	2.19	2.09	26
	3-1-2	8.23	2.26	2.99	27
	3-1-3	8.79	2.38	2.58	29
Floor	4-1-1	40.80	6.97	2.89	46
	4-1-2	45.6	6.43	2.46	48
	4-1-3	42.5	6.82	2.99	50