**4. Verification with Field Data**

In order to verify the rationality of the above-mentioned risk evaluation method, the in-situ monitoring data were analyzed in the north end slope of Shengli #1 coalmine. The anchor monitoring points are arranged to monitor the axial force variation of the anchor cable and the displacement parameters are analyzed in the north end of the slope. Field layout with 4 anchor monitoring points and regional failure of a certain landslide in the north end slope is shown in Figure 3. The correlation laws were obtained by field monitoring results of the slope sliding in the north end slope of the open-pit mine in 2016, the axial force variation of the anchor cable in 2016, the rainfall in 2016 and the displacement of the north slope of the slope. The GPS monitoring displacements before and after the landslide accident are presented in Figure 4. The axial force variation of the anchor cable of the north end slope in 2016 are presented in Figure 5, and the rainfall and the displacement of the north side in 2017 are presented in Figure 6.

**Figure 3.** Field layout with 4 anchor monitoring points and regional landslide in north end slope.

The maximum angles of 975–1015 level and 915–945 level in the north end slope are 45◦ and 57, respectively. It can be seen from Figures 4–6 that the slope of displacement curve started to be relatively flat, then increased first and then decreased, and finally the slope gradually restored stability from June 16 to June 30. The maximum horizontal displacement of 915–945 level is 210 mm and that of 975–1015 level is 190 mm. Meanwhile, the horizontal displacement of 915–945 level (larger angle) is larger than that of 975–1015 level (smaller angle). The average angle of the north slope is larger than that of the southern slope. Historical data show that the frequency of landslides in the north slope is higher than in

the southern slope, so the geometric angle of the slope has a greater impact on the stability of the slope. In March and June, 2016, the anchor cable axial force suddenly increased, and the maximum change occurred at the monitoring points of No. 1 and No. 3 which are located in the old landslide area. The above results indicate that the high slope has a potential landslide risk. The horizontal displacement and settlement of the slope in 2016 are much larger in the rainy season than in other months, which indicates that the precipitation conditions have a greater impact on the stability of the slope. The above statistical results are consistent with the risk evaluation results of the interval trapezoidal fuzzy soft set proposed in this work.

**Figure 4.** Displacement curves of the north end slope from 16 June to 29 June 2016.

**Figure 5.** Axial force variation of anchor cable for the north end slope in 2016.

**Figure 6.** Rainfall and displacement curves of the north end slope in 2017.
