The portal section of Wailongbei tunnel is shallow buried,and the buried depth is 3.0-23.38 m.The geological conditions are complex,and the portal section is located in colluvial deposit with dense and unclear distribution of boulders.The lower fully-weathered rock layer has low strength and is soft and plastic.There are uncertain factors in the construction of extra-long double-layer pipe roof.Based on this engineering,this paper summarizes the construction technology of the tunnel portal section with unfavorable geology,including the portal section reinforcement construction technology and the tunnel body construction technology in the portal section,which can provide reference for similar engineering construction.
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