# Design of Unmanned Road Widths in Open-Pit Mines Based on Offset Reaction Times
## 3 Case study and Results
### Economic Benefits of Unmanned Road Building  
This case study examines the Shengli West No. 1 Surface Coal Mine, situated 5 km north of Xilinhot City, Xilingol League, Inner Mongolia Autonomous Region. The coal seams in this surface mine have a dip angle of less than 5\({}^{\circ}\) and the primary seams are the No. 5 and No. 6 coal seams. The No. 5 seam has an average recoverable thickness. The first mining area hosts the No. 5 and No. 6 coal seams, with average thicknesses of 15.6 m and 32.23 m, respectively, while the latter is 31.4 m in the same area. A total of 13 stripping steps and 5 mining steps are present, with the heights of the stripping steps being 15 m and 10 m. All findings are based on the extraction of the non-grainy coal seams. The No. 6 coal seam in the initial mining region has an average thickness of 32.23 m, while the average thickness of the No. 6 coal seam in the same area is 31.4 m. The height of the stripping steps here stands at 15 m, whereas the coal mining steps have heights of 10 m and 15 m. Presently, there are 13 stripping steps and 5 coal mining steps. The transport equipment available for use mainly includes 91 t, 108 t, and 220 t mining dump trucks, with over 50,220 t dump trucks being operational. Figure 6 shows a 3d diagram of the Shengli open pit mine. Figure 5: Tire model made using Trucksim. Figure 6: A 3D diagram of the Shengli West No. 1 Open-Pit Mine. The previously calculated \(x_{op}\) only represents the optimized width of a single lane and a single side of the mining truck. Therefore, the optimized width of the road surface for dual vehicles is \(x_{d}=4x_{op}=6.972\) m and the optimized width for single-vehicle road surfaces is \(x_{s}=2x_{op}=3.486\) m. The average length of the southern slope at Shengli West No. 1 Open-Pit Coal Mine is 1000 m. The optimized transportation road width is utilized to determine the profile structure of the southern slope following lane compression according to the \"Preliminary Design Specification for 2800 Mt/a Shengli Energy Shengli No. 1 Open-Pit Coal Mine\" on the division of steps along the south slope road. As shown in Figure 7, after the optimization of the end slope road width, the stripping volume is 3,273,500 m\({}^{3}\), the coal production volume is 2,496,280 t, and the stripping ratio to the slope is 1.31. Based on the lithology of the Shengli West No. 1 Open-Pit Coal Mine's stratum, we analyzed the stability of the south slope before and after optimization. Table 3 illustrates the physical and mechanical properties of the slope rock body during the stability analysis of the open-pit mine. Based on the stratigraphic structure of the south slope and the principle of the limit equilibrium, a two-dimensional stability analysis method was employed to examine the landslide modelling of slopes. The resulting analysis showed the location of the potential sliding surface and the extent of the sliding body throughout the slope. The stability of the south slope profile was analyzed using the Morgenstern method in conjunction with the slope stability analysis software SLOPE/W 11.4.0.18. The impact of mine dump truck loading on the slope stability was also taken into account to identify the most hazardous sliding surface of the south slope. The results of the slope stability analysis are presented in Figure 8.  
Requirements for open pit mine slope stability coefficients [21], end slopes with a service life of less than 10 years must have a stability coefficient of at least 1.10. Figure 8 shows that both the original slope and optimized slope stability coefficients exceed the required specifications, indicating that the south slopes are stable.