Research On Secondary Sealing Technology With Pressure And Drainage Optimization Of Changping Mine

Gas extraction is the fundamental measure for the prevention and control of gasdisasters and accidents in coal mines, the quality of hole sealing of gas extraction andeffective extraction cycle determines the effects of mine gas extraction, and gasextraction rate is one of the important technical parameters measuring extractioneffects, so the effective technology of hole sealing of extraction from borehole is veryimportant to improve the extraction rate. At present the traditional sealing technologyalmost never involved in the effect of desorption gas and drainage negative pressureof borehole surrounding rock on the gas extraction in the process of extraction. In theinitial stage of the gas extraction the gas concentration is higher, and it can achievethe desired effect, but with the extension of gas extraction system, the surroundingrock fracture of the extraction from borehole rapidly develops, extends, deforms and alarge number of secondary fractures comes under the comprehensive function of theeffective crustal stress, desorption gas and drainage negative pressure, and the holesealing section and the drill hole wall or its surrounding rock fissure form "leak"channel, causing orifice extraction pressure falls sharply in the later stage, whichreduces the effect of the gas extraction and shortens the cycle of effective extractionfrom drilling, having a serious influence on the gas extraction rate in the coal seam.Asthe surrounding rock of the borehole produces a large number of pores and fissures inthe process of the gas drainage in coal seam, it bring about many technical problemssuch as gas drainage concentration drop, and effective drainage period is also shorted.Then the technology for the new secondary hole sealing under pressure called―Reserved Plug, Secondary Grouting‖was proposed.According to the theory of damage-fracture mechanics for coal and rock mass,this paper researches fracture development and propagation mechanism of thesurrounding rock of the drainage under suction borehole and builds the correspondingphysical mechanical model. In view of the shortcoming that when the bore is sealedfor the first time, the surrounding rock of the drainage holes has a poor sealing, thispaper clarifies the principle, device structure and hole sealing process of the newsecondary hole sealing under pressure, and studies the corresponding hole sealingdevice and process, and also it has made significant effect of extraction in the Changping coal mine of Jin Coal Group. The field application shows that compared with thetraditional hole sealing technology and bursa bag hole sealing technology, the technology of the new secondary hole sealing under pressure takes a leading positionin the extraction effect of hole sealing. By optimizing the radius of gas drainage,improving hole sealing technology, the average concentration of the gas extraction,the average pure traffic of the gas extraction of a single drainage borehole and theaverage effective extraction time of the single-hole get to41.6%，5.0L/min�'�43.8d,and compared with the intact hole technology in Chang ping coal mine, theyrespectively improve by11.1%、1.1L/min and22d, and the gas concentration caneffectively improve to more than35%in the late extraction.