Observe the temporal evolution of deep tunnel's 3D deformation by 3D laser scanning in the Jinchuan No. 2 Mine

The three-dimensional (3D) deformation of underground tunnel is meaningful for assessing its mechanical stability, especially for the tunnel with large deformation disaster. In this study, a technology for measuring the 3D deformation of tunnel is presented based on a 3D laser scanner and processing algorithm for point cloud data. This technology includes splicing technology for multi piece point clouds in the same time, filtering technology for 3D point cloud data at individual times, alignment technology for point cloud data from different times, and data extraction technology for typical cross-section deformation of the tunnel and calculates the 3D deformation of the tunnel at different times. This technology was applied to monitor the temporal evolution of the 3D deformation of a deep tunnel in the Jinchuan No. 2 Mine, where the large deformation of the surrounding rock caused serious failure of the supporting structures. The resulting characterization of the dimensional and temporal deformation process of the surrounding rock in the Jinchuan underground tunnel included the 2D deformation distribution characteristics of the cross section, the spatial deformation distribution of the tunnel's 3D surface, and the 4D spatiotemporal evolution process of the tunnel's deformation. The observed results provide key information for predicting deformational performance and determining the reasonable support opportunity for a tunnel undergoing large deformation problem.