Research On Deformation Of Existing Subway Tunnel Caused By Excavation Construction

With the development of urbanization in China, the development and utilization of underground space has received more and more attention, resulting in a large number of the city’s bustling area of excavation. Often, the pit in the city area are surrounded by communication lines, underground pipelines, subway tunnels, and other municipal facilities, leading to very complex construction environments. Such excavation not only relate to itself security and stability, but also nearby buildings and structures are affected.Subway tunnels have strict restrictions on deformation, while excavation of pit nearby is bound to cause deformation of the surrounding soil. If construction is improper, it will affect the operation of the subway tunnel nearby, or even cause safety problems. In this paper, by using theoretical analysis as a guide, numerical simulation of deformation induced by excavation adjacent existing tunnel are analyzed. The main contents and conclusion are as follows.1. The research on tunnel deformation caused by the excavation of nearby pit is concluded. The pit and tunnel deformation theory, factors and related theoretical calculation method are summed up.2. By using single variable method, changing horizontal relative position between pit and tunneling while keeping their vertical relative position unchanged, the whole process of excavation are simulated and analyzed with software FLAC3 D. By this way, the relationship between their vertical relative position and tunnels’ horizontal and vertical deformation are researched. The results show that with the reducing of the distance, the tunnel’s deformation shows an increase. Under the geological conditions mentioned by this paper, 2 meter is the critical position. If less than this value, the deformation of the tunnel will not meet regulatory requirements and special construction methods or tunnel reinforcement are required.3. By using single variable method, changing vertical relative position between pit and tunneling while keeping their horizontal relative position unchanged, the whole process of excavation include two circumstances: tunnel located on the side and under the pit are analyzed. By this way, the relationship between their horizontal relative position and tunnel’s horizontal and vertical deformation are researched. The results show that with the reducing of the distance, the tunnel’s horizontal and vertical deformation both increase, and vertical deformation is dominant. Because of soil uplift, tunnel shows a more severe vertical deformation when located under the pit and 4 meter is the critical position. When the distance is larger than 10 meters, excavation has little effect on the tunnel deformation.