Three-dimension safety monitoring for Beijing subway tunnel

Urban subway is the main part of the Beijing's high-capacity public transportation system. With the fast development of the metropolis modernization, the underground engineering construction must lead to the deformation of the adjacent subway tunnel, thus endanger the stabilization and safety of the whole urban transportation system. The safety monitoring for subway tunnel is an important procedure of guaranteeing transportation safety. This paper puts forward a method of three-dimension digital deformation monitoring for urban subway. It can obtain the 3D digital data of the subway tunnel deformation which do not interrupt the subway transport. It not only can precisely monitor the deformation of the tunnel liner and the railway to ensure the safety of the subway, but also expediently provide mechanics analysis on the deformation of tunnel construction and the rail. The paper discusses how to build the 3D model for the subway tunnel and the rail by the ground lidar surveying technology. Then Use the Georobot to survey the deformation of the tunnel cross section and the rail automatically. According to data processing and analysis using a model interpolation method, the 3D digital model of the deformation and displacement for the whole tunnel is fitted finally. Thus we can obtain the 3D stereo image of the subway deformation. It plays an important role in guaranteeing transportation safety of Beijing subway.