Abstract: The rapid identification and extraction of tunnel steel arches supporting structures based on 3D point cloud scanning is the key link in the process of intelligent perception for tunnel special equipment. Due to the limitations of tunnel construction environment and cost, the point cloud scanned by special equipment trolleys lacks the strength information, which increases the difficulty of extracting and segmenting the point cloud of steel arches. Aiming at this problem, a method for detecting and extracting tunnel steel arches based on point cloud space projection features is proposed. Firstly, the tunnel point cloud is projected spatially according to the tunnel axis and transverse plane, forming a projected image based on the tunnel cross-section. Secondly, based on the characteristics of the point cloud projection distribution of steel arches, combined with the digital image method, the projection area of steel arches is detected. Finally, the point cloud of the steel arch supporting structure corresponding to the projection area is extracted to analyze the position and state of steel arch. This method ensures the accuracy and flexibility of arch extraction based on single-site cloud scanning data by setting projection parameters, and can be applied to the identification and positioning of steel arches when covered by shotcrete during wet spraying.

Key words: tunnel point cloud, arch identification, spatial projection, image detection, arch positioning