Technology of Three-arch Structure Subway Tunnel Construction in Sand and Gravel

The three-arch structure in shallow underground excavation of subway stations has been adopted more and more common.Most of the mining structure using safe,good flexibility,easy to operate,the low level of mechanization,unearthed efficient process with less interference in the construction technology hole.The three-arch tunnel on Shiliuzhuang Subway Sation of Line 4 in Beijing Metro passes through the ground consisting of silty clay and medium-coarse sand,which is constructed by means of the center drift method.The central drift of the tunnel is excavated first,which is followed by the excavation of the side drifts.The conversion of the force-bearing of the tunnel during construction is very complex and the settlement occurring in different excavation steps has great impaction the settlement of ground.By means of adopting proper construction methods and modifying the reinforcement parameters on the basis of the monitoring data,the safety and stability of the tunnel are guaranteed and the difficult problems are solved.