砂卵石地层地铁隧道下穿既有隧道影响分区与控制研究

Study on the Influence Zone and Control Technology of Subway Tunnel of Sandy Cobble Stratum underneath Passing Existing Tunnels

以成都地铁5号线下穿地铁3号线为工程背景,运用有限差分软件FLAC3D,研究合理的影响分区,并论证CRD工法在下穿既有隧道时的应用效果。研究结果表明:新建隧道对既有隧道的影响与埋深呈正相关,与净距呈负相关;影响分区揭示了大部分在成都砂卵石地层进行的既有隧道近接施工均需要采取相应的控制措施,以保证施工安全;CRD法可以有效地控制成都砂卵石地层强影响区近接施工对既有隧道的影响,弱影响区可采用注浆加固以及超前支护等方法进行控制。

Taking Chengdu Metro Line 5 underneath passing Metro Line 3 as the project background,the finite difference software FLAC3D was used to explore the reasonable influence zone,and the application effect of CRD method undercrossing existing tunnel was demonstrated.The results of research show that the influence of new tunnel on existing tunnels is positively correlated with the buried depth,and negatively correlated with the net distance.The influence zone reveals that most of the adjacent construction of existing tunnels in the sandy cobble stratum of Chengdu needs to take corresponding control measures to ensure the construction safety.The CRD method can effectively control the impact of the adjacent construction on the existing tunnel in the strongly affected area of the sandy cobble stratum in Chengdu and the weak affected area can be controlled by grouting reinforcement and advanced support.