Safety Mining Technology of Coal Seams in Weathered Zone Based on Ground J-Type Pregrouting Reinforcement

Table 1

Mechanical properties of coal and rock.

Lithology	Cohesive force (MPa)	Internal friction angle (°)	Uniaxial compressive strength (MPa)	Elastic modulus (GPa)	Poisson’s ratio	Tensile strength (MPa)
Unconsolidated layers	12.89	34.70	92.10	25.35	0.20	15.54
Loading layer 2	3.16	41.30	34.51	9.87	0.25	4.93
Soft rock	4.50	38.5	30.5	10.56	0.28	3.82
Loading layer 1	5.36	42.50	35.28	11.45	0.24	5.19
13# coal	0.48	28.6	7.65	2.96	0.30	0.86
Floor strata	7.69	40.60	45.68	15.36	0.23	7.85