Abstract: In view of the shortcomings of traditional measurement methods, such as single results, complex process and low efficiency, in the extraction of metro tunnel cross-section and deformation monitoring, a surface fitting method based on the least square method is proposed for section extraction and deformation monitoring analysis using TLS technology in this paper. In this method,the continuous section of the tunnel is extracted based on the central axis of the tunnel, and the truncated section is fitted to a synthetic surface.The horizontal and vertical variation dimensions of the fitted surface are obtained through multiple surface comparisons, and then the deformation of the metro tunnel is calculated.Taking a tunnel in Xi'an metro as an example,compared with traditional monitoring methods,the proposed technique can quickly extract tunnel section and monitor deformation,effectively improving work efficiency.

Key words: TLS, metro tunnel, section extraction, deformation monitoring