The Huayingshan tunnel of Chongqing-Guangan expressway shall pass through the two sets of coal-bearing strata,the Triassic Longtan Formation and the Triassic Xujiahe Formation on both wings of the Guanyingxia anticline.Combined with the construction of tunnel left exit passing through the Z2K26 + 250 prominent coal seam,this paper introduces the measures of pre-drainage for outburst prevention at coal opening in the large & long tunnel under complex geological conditions,expounds the gas drainage scheme,the system design and the control of the process parameters,which can provide reference for similar projects.%渝广高速公路华蓥山隧道需穿越观音峡背斜两翼的三叠系须家河组和背斜核部二叠系龙潭组2套煤系地层.结合该隧道出口端左线穿越Z2K26+250突出煤层段的施工情况,介绍复杂地质条件下长大隧道揭煤预抽防突措施,阐述瓦斯抽放方案、系统设计以及工艺参数控制等,为类似工程施工提供参考.
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