Evolution Mechanism of Thickly Sticky Loose Layered Arch Structure and Prediction Method of Initial Ground Fissure Caused by Underground Coal Mining

Table 2

Determination of ground fissure generation.

Main key layer’s collapse situation		Advancing distance of coalface/m	Loose layer arch structure			Determination of ground fracture generation
			Span/m	Arch height/m	Arch thickness/m	/kPa	Judgment
First break		24	9.37	3.89	1.65	34.4	No
Cycle breakage	1	32.01	17.38	7.03	2.79	66.63	No
	2	40.02	25.39	9.98	3.73	102.0	Yes