Experimental Study on Stress Evolution and Microseismic Signals under Vibration Conditions of Coal during Excavation and Subsequent Waiting Time

Table 1

Excavation load.

Stage and process		Excavation footage (mm)	Footage summed (mm)	Excavation time (min)	Excavation speed (mm/min)
First stage		10	10	—	—
Second stage	First excavation	15	25	8	1.875
	Second excavation	15	40	8	1.875
Third stage	First excavation	25	65	8	3.125
	Second excavation	25	90	8	3.125
Fourth stage	First excavation	35	125	8	4.375
	Second excavation	35	160	8	4.375