Abstract
Abstract Accurately estimating the volume of earthworks is very important in mining engineering and construction. This estimation can be difficult because of the morphological condition of the stockpiles, hence, devising simpler, yet accurate methods of stockpile volume estimation is still a research problem in mining. Two non-invasive survey methods were compared in this research: the conventional ground-based and UAV-approach, for the survey of a twin-stockpile of gravel using Leica TS06 Total Station and DJI Mavic Air UAV, respectively. About 128 images of the area were acquired at 50 m flying height and 75% overlap during the flight mission. The images were processed using Agisoft Metashape Pro; a digital photogrammetric software, and the DEM obtained was used for the volume estimation. The total station data was also processed in ArcGIS to generate a TIN-model from which the volume was also estimated. The volume estimated from the TIN-model was compared with the volume estimated from the UAV-based DEM, using the volume obtained from the mill-machine as the standard. The obtained result shows that while 2750 m3 was obtained as the cumulative volume from the mill machine, the UAV approach yielded 2686.252 m3 and the ground survey approach gave 2830.713 m3. The percentage difference between the two methods compared to the actual volume is 2.94% and −2.31%, respectively. These results, and the result of the processing time analysis show that UAV approach is both accurate and time economical, which attests to the potentials of low-cost UAVs to provide robust alternative to the time-consuming and rigorous ground survey approach.
Highlights
Stockpile is a term used for a large collection of mining and construction materials, such as sand, gravel, asphalt, large rocks, and so on, that are stored in reserve for future use or at time of shortage
The reconstructed Digital Elevation Models (DEM) has a resolution of 4.42 cm pix−1 and point density of 513 pts m−2, while the Triangular Irregular Network (TIN) model was generated with the spatial details of the 58 points that were acquired during the field work
The applicability and robustness of unmanned aerial vehicle for earthwork volume estimation was investigated. It explored the application of high-precision non-invasive survey technologies for the assessment of the volume of earthworks, using a twin stockpile situated in a quarry site as a case study
Summary
Stockpile is a term used for a large collection of mining and construction materials, such as sand, gravel, asphalt, large rocks, and so on, that are stored in reserve for future use or at time of shortage. The predominant method of acquiring necessary data needed for the estimation of volumetric information is the conventional terrestrial or ground based survey method where. The total station is an electronic transit theodolite integrated with an Electronic Distance Meter (EDM) to read slope distances from the instrument to a particular point (Kavanagh and Glenn 1996). These data are recorded electronically to an accuracy of ±20 mm and processed in order to generate 3D model of the stockpile from which the volume of the earthworks will be determined. Apart from the dangers posed by the risky terrain of mining sites, this method has proved to be expensive and time consuming, the need for alternative approaches
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