Study on Deformation and Fracture Evolution of Underground Reservoir Coal Pillar Dam under Different Mining Conditions

Table 4

Orthogonal experiment range analysis Tab. (maximum vertical stress).

Factor	Length of working face/m	Width of coal pillar/m	Mining height/m	Water pressure/MPa
Average results of the first level	39.95	51.82	44.12	44.85
Average results of the second level	45.29	47.60	45.99	46.23
Average results of the third level	48.55	44.03	46.81	46.59
Average results of the fourth level	50.96	41.29	47.82	47.08
Range	11.02	10.53	3.70	2.23