Abstract: Shield tunnel convergence monitoring is an important monitoring indicator for metro operation detection. It focuses on the inadequacy of traditional monitoring equipment and monitoring methods such as convergence rulers, total stations, cross-section meters, Bassett convergence systems, and station scanners. This paper proposes a novel convergence monitoring method based on mobile 3D laser scanning. Mobile 3D laser scanning technology uses a 2D cross-section scanner combined with a variety of sensors such as mobile rail cars, inertial navigation and positioning, and encoders to work together to obtain point cloud data of the tunnel structure through manual scanning. Analysis of convergence of tube segments. The fast and comprehensive monitoring of the cross section convergence of the subway tunnel is made up for the shortcomings of low efficiency and incomplete cross section monitoring of traditional convergence monitoring. The results of engineering application examples show that this method can not only achieve fast and efficient monitoring of tunnel cross-section convergence, but also the massive point cloud data obtained can be further deepened, providing basic data guarantee for subway tunnel safety monitoring, and ensure the safe operation of the subway.

Key words: shield tunnel, operational inspection, convergence monitoring, mobile 3D laser scanning, 2D cross-section scanner