# Risk Analysis of Service Slope Hazards for Highways in the Mountains Based on ISM-BN
## 3 Selection of Factors for Operating HSD Risk in Mountainous Areas
### Influencing Factors of HSD Risk in Mountainous Areas  
It was found that the main influencing factors of disasters on service slope include meteorological environment, slope geotechnical characteristics, slope height, slope support structures, slope drainage facilities, design quality, construction quality, maintenance quality, and travel load by analyzing the historical disaster events of multiple typical service slopes of several operating highways in the Dabie mountain area and the southern Anhui mountain area of Anhui from 2015 to 2020 [28]. The research by [PERSON] et al. [29] showed that the slope hazard risk is sensitive to engineering geological conditions and topographic and geomorphic conditions. The results obtained by [30] have indicated that most of the highway retaining wall failures around the world occurred due to missing or inadequate drainage systems. In addition, other scholars have also identified numerous risk factors that affect the performance of highway slopes in their studies on specific slopes, as shown in Table 1.  
It is clear that the formation of slope hazards may be affected by a combination of one or more of these factors. In order to make the relevant influencing elements comprehensive and representative, based on the existing literature, after several rounds of expert discussion, the fishbone diagram analysis method was chosen to sort out the influencing factors of slope disaster risk for mountain highways. The influencing factors of slope disaster risks of the mountainous highway in service can be categorized into four aspects, namely environmental factors, slope technical conditions, disaster-bearing sets, and management factors. The fishbone diagram was constructed to analyze the disaster risk of the service highways in mountains, as shown in Figure 2. \begin{table}
\begin{tabular}{c c} \hline
**Literature** & **Relevant Influencing Factors** \\ \hline
[31; 32] & Rainfall intensity, slope gradient \\
[13] & Surface runoff, groundwater \\
[33] & Engineering geological conditions, extreme climate events, human activities \\  & Slope disease history, damage to supporting structures, damage to drainage \\
[34] & facilities, geological engineering conditions, hydrogeological conditions \\
[35] & Micro-topography, hydrological conditions, average annual precipitation days, \\  & geotechnical type, vegetation coverage \\
[36] & Engineering geological conditions, topography, construction quality, slope \\ \hline \end{tabular}
\end{table} 
Table 1: Research on the influencing factors of expressway slope risk. 1. Environmental factors specifically include the influences of six factors: engineering geological conditions \(X_{1}\), hydrological and hydrogeological conditions \(X_{2}\), micro-topography and landform \(X_{3}\), annual precipitation \(X_{4}\), daily maximum rainfall \(X_{5}\), and the lowest monthly average temperature \(X_{6}\). 2. The technical conditions of the slope specifically include the influences of 10 factors: soil properties \(X_{7}\), soil compaction \(X_{8}\), soil moisture status \(X_{9}\), shear strength \(X_{10}\), slope height \(X_{11}\), slope gradient \(X_{12}\), slope disease history \(X_{13}\), support structure status \(X_{14}\), drainage facility status \(X_{15}\), and slope stability level \(X_{16}\). 3. Management factors specifically include the influences of four factors: design quality \(X_{17}\), construction quality \(X_{18}\), maintenance quality \(X_{19}\), and traffic load rating \(X_{20}\). 4. Disaster-bearing set. It is of no practical significance to discuss risk without considering the disaster-bearing objects.