Study On Slope Deformation Monitoring Of Open-Pit Mine Based On Close-Range Photogrammetry

Slope is formed in the process of open-pit mining,and with the continuous excavation of the slope,the slope is getting larger and larger,which is prone to the occurrence of disasters caused by slope instability.Therefore,it is necessary to monitor and analyze the stability or deformation of the slope through corresponding technical means.Close-range photogrammetry technology can quickly obtain high-quality image data of the target without touching the target,and then establish a high-precision 3D model of the target by processing the image data.Therefore,this technology has been widely used in slope deformation monitoring.In this paper,close-range photogrammetry was applied to the slope deformation monitoring of Yuebao open-pit mine in Guangzhou.Firstly,the normal digital camera was checked and then the camera calibration parameters was obtained.A complete slope point cloud data was obtained by fusing 3D laser scanning data and close-range photogrammetric data using point cloud fusion method.DEM model is obtained from slope model reconstruction,and form variable and deformation area of slope are obtained by superposition analysis of DEM and slope profile line.The main results is as follows:(1)The camera calibration parameters were solved by the resection method based on 3D control field and the calibration method based on vanishing point.By analyzing the camera calibration parameters,it was concluded that the main point and the main distance F value of the camera were relatively stable,but the distortion coefficient had some certain dispersion.After analyzing the coordinate difference of the marked points,the result of the calibration meets the precision requirement.After analyzing the error in the coordinate of the marked points,the multi-slice resection method is selected to obtain the result as the calibration parameter in the data processing process.(2)Registration and mosaic of 3D laser scan data and close-range photogrammetry data will generate multi-layer and uneven distribution of point cloud in the overlapping area of data.This paper used the point cloud data fusion method based on normal constraint to fuse 3D laser scan data and close-range photogrammetry data.The fused point cloud data can not only make up the void of the slope model,but also show on the subtle features.At the same time,the obtained fusion surface was smoother and the fused point cloud distributed more evenly at the point cloud boundary.(3)By DEM superposition analysis and profile analysis of the slope.The results showed that landslides occurred in some areas of the slope mainly in July and October,and the maximum deviation was 4.8912 m /-3.2065 m.According to the statistics of the number of point clouds and the percentage histogram of the slope deformation range,the deformation range of the slope presented a normal distribution.Combining with the value of the deformation range,we can know that the deformation area of the slope is mainly located in the southern mining area.The landslide mainly occurred in the slope area of 30-40 degree.According to the aspect value,it can be known that the slope direction belonged to the east slope,and a small part of the slope belonged to the North Slope and the northeast slope.The landslide direction of the slope was mainly along the east direction.