# Analysis of Mining Waste Dump Site Stability Based on Multiple Remote Sensing Technologies
## 4 Discussion of Experimental Results
### Numerical Simulation Based on the LE Method  
In LE simulation, the factor of safety (FOS), which is the ratio of anti-sliding force to sliding force, is calculated for each slope respectively. Theoretically, a FOS less than 1.0 indicates that there is already sliding damage. The specifications for design of highway subgrades (JTG D30-2015) stipulates that the FOS threshold for a road slope is 1.35, meaning that coefficients smaller than 1.35 indicate instability. Unfortunately, there is no clear regulation for mining dump sites. Taking some unforeseen complex situations into consideration (e.g., abnormal weather phenomena), a FOS larger than 1.2 is considered to meet the requirements for safety and stability. The simulation results for both assumptions are shown in Figure 14, where (a-c) are simulation results based on the plane sliding surface assumption, and (d-f) are simulation results based on the circular arc sliding surface assumption. The blue lines in Figure 14 represent the slope surface, and the red lines indicate the detected dangerous sliding surfaces for each profile. The simulated FOS in Simulation 1 is shown in Table 2. It is clearly shown that the total FOS of profile KK\({}^{\prime}\) was the largest, whereas that of NN\({}^{\prime}\) was the smallest of the three. A total FOS of 1.08 indicated that profile NN\({}^{\prime}\) was the most dangerous slope in this simulation. By comparing the different coefficients of the three sections of profile MM\({}^{\prime}\), we could tell that the higher section was more dangerous than the middle section, and the lower section was the most stable. The situation at profile NN\({}^{\prime}\) was slightly different than that of MM\({}^{\prime}\); the middle section was the most dangerous. In this simulation, only profile NN\({}^{\prime}\) showed a FOS value less than 1.2. The other two profiles were generally stable according to Simulation 1. The least favorable situation and potential failure surface was found in the second simulation, as shown in Table 3. Compared to the first simulation, the FOS in the second simulation was generally smaller. Nevertheless, the FOS for profile NN\({}^{\prime}\) was still the smallest, whereas the coefficient for profile KK\({}^{\prime}\) was the largest of the three. The FOS of profiles MM\({}^{\prime}\) and NN\({}^{\prime}\) were both smaller than 1.2, indicating that the two profiles are quite unstable. The critical FOS value of 1.0139 of profile NN\({}^{\prime}\) means that this profile has most likely moved. The results from both simulations are consistent with each other. From the FOS values we can tell that profile KK\({}^{\prime}\) is quite stable, with two FOS larger than 1.2. The smallest FOS of profile NN\({}^{\prime}\) is 1.0139, indicating that this slope profile has probably been destructed. The obvious collapse and fissure found near profile NN\({}^{\prime}\) during field investigation (Figure 15) also supports the conclusions of both simulations. Unfortunately, the FOS for profile MM\({}^{\prime}\) is also smaller than 1.2, indicating that it is also quite dangerous. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Profile Name**} & \multicolumn{2}{c}{**Slope 1 (Lower Part)**} & \multicolumn{2}{c}{**Slope 2 (Middle Part)**} & \multicolumn{2}{c}{**Slope 3 (Higher Part)**} & \multicolumn{2}{c}{**Total**} \\ \cline{2-9}  & \(\mathbf{K_{2}}\) & \(\mathbf{\delta}\) & \(\mathbf{K_{2}}\) & \(\mathbf{\Delta}\) & \(\mathbf{K_{2}}\) & \(\mathbf{\delta}\) & \(\mathbf{K_{2}}\) & \(\mathbf{\delta}\) \\ \hline KK\({}^{\prime}\) & 2.70 & 21 & 1.69 & 29 & - & - & 1.69 & 29 \\ NN\({}^{\prime}\) & 2.71 & 19 & 1.51 &Figure 14: The simulation results along profiles KK\({}^{\prime}\), NN\({}^{\prime}\) and MM\({}^{\prime}\). The blue lines represent the slope surface, and the red lines represent the dangerous sliding surface. (**a–c**) are simulation results based on the plane sliding surface assumption, and (**d–f**) are simulation results based on the circular arc sliding surface assumption.