Evaluation Method of Floor Heave Damage Degree and a Case Study in Zaoquan Coal Mine, China

Table 3

Evaluation standard for the ground stress level of underground engineering [17].

Geostress level	High ground stress problem	Rock burst strata	Compressional strata	General strata
		Potential rock burst index Ω	Stress evaluation index
Low to medium	Nothing	<0.4	>1	>7
	Slight	0.4∼1.05	1∼0.63	4∼7
	Secondary	1.05∼2.5	0.63∼0.45
High	Severe	>2.5	0.45∼0.32	<4