摘要
Abstract
High gas fragmented soft coal seams have the characteristics of low coal body strength and high gas content.During the drilling process,the deformation amount of the borehole is large,and it is prone to instability and damage,resulting in collapse of the borehole.This leads to shallow drilling depth and low drilling efficiency,which affects the efficiency of gas extraction.In order to improve the application effect of grooved drill rods in fragmented soft coal seams,key parameters such as the heads number of spiral trough body,pitch of screw,trough depth,and trough width are considered.A numerical calculation method of gas-solid interphase coupling with EDEM and Fluent is used to construct a slag discharge model for grooved drill rods,and the influence of structural pa-rameters of grooved drill rods on slag discharge performance is compared and analyzed.The results show that increasing the heads number of the spiral trough body is beneficial for increasing the slag discharge space and improving the slag discharge effect of drill rods;for a Ф 50 mm small diameter grooved drill rod,the spiral trough body on the surface of the drill rod is designed as a three headed structure,which significantly improves its slag discharge performance compared to single headed and double headed troughs;when the design of screw pitch of the triple helix grooved drill rod is 252 mm,the trough depth is 2.5 mm,and the trough width is 16 mm,the slag discharge effect of the drill rod is optimal.Through on-site industrial experiments,the drilling effect is compared with that of circular drill rods used in coal mines.The drilling depth of the triple helix grooved drill rod is in-creased by 11.5%,the drilling efficiency is improved by 35.4%,and the hole completion rate reaches 100%.During the drilling process,there is no phenomenon of jamming or breakage of drill rods happens.关键词
松软煤层/钻屑/槽体结构/钻孔排渣Key words
soft coal seam/drilling chip/trough structure/drilling and slag discharge分类
矿业与冶金
