55 / 2023-03-30 22:56:41

Overall safety monitoring method of tunnel based on cubic B-spline adaptive fitting

Point cloud,Cubic B-spline,Cross-section,Safety monitoring,Mine tunnel

Mine tunnel is an important working and transportation channel in the mine, and its safety is directly related to the mine production and staff safety. Tunnel deformation will affect the smoothness of mine transportation, increase transportation costs and affect the economic benefits of the mine. Severe deformation can also lead to ground subsidence, landslides and other geological disasters, causing serious impact on the surrounding environment of the mine. Therefore, safety monitoring of mine tunnel is of great importance. It can guide the prediction and control of tunnel deformation and damage, guarantee the safe and stable operation of the tunnel, reduce the probability of accidents, and improve the productivity of the mine.

Currently, traditional measurement methods such as total stations, pressure gauges, and acoustic sensors are commonly used for safety monitoring of mine tunnel. These methods require manual installation of equipment for measurement, which is labor-intensive, time-consuming, and expensive. Moreover, the single-point measurement method can only reflect local characteristics and cannot achieve global safety monitoring. With its unique advantages, 3D laser scanning technology can obtain 3D information of the target object quickly, accurately, comprehensively and without contact, thus the application practice of 3D laser scanning technology in mine monitoring is increasing. However, there are still many problems in the processing and analysis of tunnel point cloud data that need to be solved. For example, the traditional two-dimensional analysis method is not fully applicable to three-dimensional point cloud data; the uneven density of point clouds and holes problems caused by the characteristics of the scanner itself and occlusion; for irregularly shaped tunnel cross-section, simple circular or elliptical fitting cannot restore the true shape of the tunnel. All these problems restrict the development of tunnel point cloud data processing.

To address this, this study proposes an overall deformation monitoring method of mine tunnel based on adaptive fitting of cubic B-spline curves. First, the 3D laser scanning technology is used to obtain a large amount of point cloud data, and the pre-processing work such as registration, denoising and subsampling is carried out; second, the bilateral projection method is used to extract the central axis of the tunnel data, and the tunnel section is extracted at any position with the axis as the reference; then, the density and normal information of the tunnel section point cloud are combined, and the thickness and attitude of the section are adjusted and corrected to accurately obtain the section point cloud; finally, the adaptive fitting of the tunnel section is carried out by using the cubic B-spline, and the section point cloud data is accurately obtained. Finally, the cubic B-spline is used to adaptively fit the cross-section, and the hollow part of the section is fitted to restore the original shape of the cross-section to the greatest extent. The 3D information of the section feature points is extracted to reflect the overall deformation information of the tunnel. The section feature points can provide elevation information as well as radial information, reflecting the changes of the tunnel in the lateral and vertical directions.

The feasibility and accuracy of this research method were verified through experiments, and the corresponding software module was developed to complete the precise extraction and adaptive fitting of tunnel cross-section, tunnel deformation analysis, and other related work. The method uses the section information of any position of the tunnel to monitor and analyze the tunnel deformation, discover the deformation in time and take corresponding measures to repair and reinforce. As a result, it can effectively reduce the hazard of tunnel deformation to the mine and guarantee the production safety and working environment of the mine.