The invention relates to an under-
pressure grouting and hole sealing device and method for gas extraction
drill air bag blocking. The device is characterized in that the device comprises an extraction
pipe, a first tip air bag, a second tip air bag, a
slurry outlet
pipe and a grouting
pipe, wherein the extraction pipe is composed of a first extraction pipe body, a second extraction pipe body and a third extraction pipe body, the first extraction pipe body is sleeved with the first tip air bag, a one-way
needle valve is arranged on the first tip air bag, the
slurry outlet pipe with a one-way
check valve arranged inside penetrates through the first tip air bag, the outer end of the
slurry outlet pipe is communicated with the grouting pipe, the third extraction pipe body is sleeved with the second tip air bag, a one-way
needle valve is arranged on the second tip air bag, the two ends of the second extraction pipe body are connected with one end of the first extraction pipe body and one end of the third extraction pipe body respectively, the tip of the other end of the third extraction pipe body is provided with a plurality of
sieve holes which allow gas to inflow, and the first tip air bag and the second tip air bag are filled with expansion agents in advance. The device and the method can be widely applied to permanent hole sealing for
coal mine underground gas extraction hole drilling.