Changing Laws of Drainage Negative Pressure Along With the Change of Drilling Depth in Fuyan Coal Industry

In order to study of drainage negative pressure change along with the change of drilling depth，it took drainage negative in different drilling depths（0 m，20 m，40 m，60 m，80 m and 100 m）as the investigation index，and carried out in Fuyan Coal Mine. The test results showed that the change laws of negative pressure change along with the change of drilling depth is accorded with the exponential decline law p=ae^-bL，the loss of negative pressure per 100 meters was 1.896 to 3.382 kPa and the average is 2.468 kPa，when orifice negative pressure was 13.00 to 46.13 kPa.