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

Table 2

Features of the microseismic signal energy and event numbers.

Microseismic signal indicator	Excavation speed during the excavation operation
	Energy per second of microseismic pulse during the excavation (mJ/s)	10.86	21.30	8.37
Event numbers per second during the excavation (1/s)	17.15	16.14	19.73
Percentage of the total time required for the energy to reach 90% during excavation (%)	54.7	82.6	87.6
Total energy during waiting time after excavation for a period of time (mJ)	2.42	6.25	53.34
Event numbers during waiting time	27.0	53.0	102.0
Energy per second during waiting time (mJ/s)	0.090	0.118	0.523