Abstract:
Aimingattheproblemofgaspre⁃drainageinhighgasandlowpermeabilitycoalseam,the strengthentechnologyofcoalseamgasextractionwasputforwardwhichisthesystemofcombinedpipe⁃ linetoliftthenegativepressureandintensivelargediameterdrill⁃holealongseam*Theextractionprin⁃ cipleofrealizingthepermeableincreasinginallzonebyintensivelargediameterdrill⁃holealongseam wasexplained*Accordingtothecontinuityliquidflowequationandenergyequation,theexpressionof liquidenergychangeswasestablishedtogetliquidenergygradientlinesinsectioncompetent pipe⁃ line*Combinedwiththe“negativepressure⁃flow”characteristiccurveofpre⁃drainagegasdrill⁃hole,the mechanismofincreasethenegativepressureandextractionscalarthroughcombinedpipelinewasclari⁃ fiedandtheparametersofstrengthenextractiontechnologyincoalseamwasconfirmedbypracticalex⁃ perience*Thepracticeshowedthatthistechnicaleffectongovernancegaswasremarkable,thegasex⁃ tractionrateinworkingfacewasabove55% andtheproductioncapacityincreasedfrom1*2Mt/ato 1*8Mt/a*Theuppercornergasconcentrationwasunderthesafetystandard,andthusthesafetyandef⁃
ficientlyminingincomplicatedgeologicalconditionswasrealized*