Gas Emission Characteristics on Large Diameter Boring and After the Blasting of Drivage

Large diameter boring as a prevention measure of gas outburst (2nd Report)

Abstract

In this paper, the measuring results of gas emission into seam road on the large diameter boring and after the blasting of drivage are described.
Main results obtained are as follows.(1) The large diameter (250 mmφ) boring was effective to relieve not only seam stress but also seam gas, particularly in fault zone. It had a marked tendency to increases the gas emission rate to the heading of seam road under such circum stances as the boring penetrates in front and rear of faults.
(2) Gas emission characteristics after the blasting of drivage is classified into seven types as shown in Fig. 8. The kind of the characteristics of places where gas was remarkably emitted in 30 minutes after the blasting was mostly patterned by type A.
(3) The mutual relation between the gas emission volume in 30 minutes after the blasting and the difference of gas concent ration before and after the blasting was able to be found.
(4) Just before the region where a large amount of gas was emitted on the large diameter boring, it was recognized that large gas emission was causedby the blasting of drivage.