Dump slope change detection and displacement monitoring using UAV close-range photogrammetry

In large open-pit coal mine projects, internal dump slope failure is a serious issue for industry. Slope failure affects haul roads, mine machinery, and miners' lives and hampers coal production operations. Dump slope failure events will not occur suddenly, and progressive displacement will occur in the slope before failure. Therefore, dump slope monitoring is essential for the safety of humans and machinery. Generally, the mine slope displacement is measured using a conventional survey approach. However, conventional surveys cannot measure minor changes in a large dump area. Therefore, massive dump displacement monitoring is a tedious task for surveyors. This study used the unmanned aerial vehicle (UAV) close-range photogrammetry survey to introduce an intelligent and reliable approach for dump change detection and displacement monitoring. A UAV close-range photogrammetry survey was conducted to collect RGB images, and dump surface point cloud data (PCD) were generated using the structure-from-motion (SfM) computing algorithm. The ground control points (GCPs) were also measured using a coordinate measurement survey for geo-reference points. For dump surface PCD and 3D reconstruction, the Pix-4D Mapper image processing tool was used. PCDs were generated for two months and used for dump slope surface change and displacement monitoring using the cloud-to-cloud (C2C) computing algorithm. The PCD was compared with the reference PCD, and the results of this investigation indicated minor and major changes on the dump slope and top surfaces. This approach is inexpensive and reliable for large dump slope change detection and displacement monitoring.