A construction method of a hydraulic flushing and presplit blasting combined permeability-increasing extraction
system in
drill holes includes the steps of (1), forming the
drill holes, namely forming a plurality of blasting
drill holes and a plurality of flushing drill holes in an extraction roadway of a
coal seam floor towards a
coal seam direction in a staggered manner, wherein a distance between each blasting
drill hole and the adjacent flushing
drill hole ranges from 3 meters to 6 meters; (2), blasting, namely mounting a steel
pipe at an orifice of each blasting
drill hole, filling a gap between the steel
pipe and the corresponding blasting drill hole with
cement mortar hermetically, filling one end of a PVC (
polyvinyl chloride)
pipe with
emulsion explosive after the
cement mortar is solidified, mounting a primer
detonator closely to the
emulsion explosive, filling a position, close to the primer
detonator, with
emulsion explosive, filling circularly sequentially and filling a position, close to the last primer
detonator, with
stemming, wherein a distance between each two adjacent primer detonators is one meter. According to the construction method,
coal seam gas permeability is improved effectively, gas extraction effects are enhanced, extraction time is shortened effectively and potential safety hazards of gas are reduced maximally.