Deformation Analysis of a Roadway Tunnel in Soft Swelling Rock Mass Based on 3D Mobile Laser Scanning.

Roadway deformation is a comprehensive response to changes in surrounding rock masses as well as the geological environment. Deformation patterns survey can help us to understand rock masses, especially soft swelling rock mass and guide roadway renovation. In this paper, an overall deformation analysis method for a largely deformed roadway in soft swelling rock mass has been proposed based on 3D mobile laser scanning. The application procedures of the proposed method mainly include point cloud data acquisition, data pre-processing, coordinate transformation, surface change detection and visualization. In the proposed method, the reference point cloud is created according to the roadway design to overcome the issue of the missing original roadway profile point cloud. By incorporating the K-nearest neighbor algorithm, a point-to-plane distance calculation algorithm is developed for the source and the reference point cloud data to detect roadway deformation. Taking the main haulage roadway in skarn rock mass at − 480 m level of Taiping Mine as an example, the deformation patterns of this roadway were analyzed using the proposed method. The results reveal that the roadway deformed seriously up to 1187 mm and the roadway deformation characterizes asymmetry and non-uniformity. The accuracy of the proposed method can meet engineering requirements by comparing the calculated and measured results. Aiming at the asymmetrical deformation patterns of this roadway, an asymmetrical support methodology has been suggested for the roadway renovation. The proposed deformation analysis method provides a reliable tool for largely deformed underground workings in soft swelling rock mass. Highlights: An overall deformation analysis method based on 3D mobile laser scanning has been proposed for largely deformed roadway in soft swelling rock mass. In the proposed method, a surface change detection algorithm has been developed by incorporating the K-nearest neighbor algorithm for the source and the reference point clouds. Taking Anhui Taiping Mine as an engineering case, the deformation patterns of the roadway in skarn rock masses have been revealed to be distinct asymmetry and non-uniformity using the proposed method. [ABSTRACT FROM AUTHOR]