# Early Detection and Stability Assessment of Hazardous Rock Masses in Steep Slopes
## 3 Method
### Stability Evaluation Index System and Weight Analysis  
When evaluating the stability of hazardous rock masses, it is crucial to establish an appropriate system for assessing indices. The selection and quantification of these indices are vital for obtaining precise analysis results due to the qualitative and uncertain nature of most influencing factors. Since UAV surveys can only capture surface-level information, it is not feasible to consider all factors when conducting stability assessments. Therefore, this study focuses on identifying the primary influencing factors. In this research, the elements impacting the stability of dangerous rock masses are classified into terrain, geological, and inducement categories. The analysis includes an assessment of each factor's contribution to the likelihood of dangerous rock disasters occurring. Geological aspects encompass parameters such as the dip angle of the main structural plane, the bottom overhang ratio, boundary crack development, and weathering; topographic features include slope and vegetation coverage. Terrain and geology reflect natural state stability whereas inducing factors involve rainfall, earthquakes, and human activities (see Figure 7). The above 9 influencing factors are selected to form a rapid evaluation index system for the stability of dangerous rock masses, and the evaluation index system for the stability of dangerous rock masses is formed in Table 3[40; 41]. Among them, the earthquake grade is judged according to the Code for Seismic Design of Buildings. \begin{table}
\begin{tabular}{c c} \hline \hline
**Argument** & **Weight (\%)** \\ \hline Slope (_Ws_) & 50 \\ Topographic correlation (_Wc_) & 25 \\ Vegetation coverage (_Wv_) & 25 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Parameter weights for terrain analysis. The issues are methodically arranged and categorized, forming a hierarchical structure model. This model is comprised of three tiers: the uppermost tier being the purpose layer, followed by the criterion layer in the middle, and lastly, the scheme layer at the bottom. \begin{table}
\begin{tabular}{l l l} \hline \hline
**Primary Index** & **Secondary Index** & **Grading Standard** & **Index Score (S)** \\ \hline \multirow{7}{*}{Geological factor (X\({}_{1}\))} & \(\alpha\geq 70^{\circ}\) & 10 \\  & Control structural plane inclination (X\({}_{11}\)) & \(50^{\circ}\leq\alpha<70^{\circ}\) & 7 \\  & 30\({}^{\circ}\leq\alpha<50^{\circ}\) & 4 \\  & \(\alpha<30^{\circ}\) & 1 \\  & & Suspension ratio L \(\geq 1/4\) & 10 \\  & Bottom hanging ratio (X\({}_{12}\)) & \(1/5<\) L \(<1/4\) & 7 \\  & & \(1/10\leq\) L \(<1/5\) & 4 \\  & & L \(<1/10\) & 1 \\  & & There are obvious signs of mis-opening & 10 \\  & Boundary case (X\({}_{13}\)) & There is a steepness through the structural plane & 7 \\  & & Surface separation cracks through & 4 \\  & & Surface separation cracks are not penetrating & 1 \\  & & Full weathering & 10 \\  & Weathering of rock mass (X\({}_{15}\)) & Strong weathering & 7 \\  & & Moderate weathering & 4 \\  & & Aeration & 1 \\  & & Precipice (\(\alpha\geq 60^{\circ}\)) & 10 \\  & Slope grade (X\({}_{21}\)) & Rock steepness (45\({}^{\circ}\leq\alpha<60^{\circ}\)) & 7 \\  & & Rocky sleep slope (30\({}^{\circ}\leq\alpha<45^{\circ}\)) & 4 \\ Topographic factor (X\({}_{2}\)) & & Dangerous rock slope (\(\alpha<30^{\circ}\)) & 1 \\  & & Weeds & 10 \\  & Vegetation coverage (X\({}_{22}\)) & Shrub trees are sparse & 7 \\  & & Trees grow into full trees & 4 \\  & & Shrub forest & 1 \\  & & Daily precipitation \(>50\))))))))))))))))))((\\\\ Rainfall action \(((((\)\)\)\)\(\)\)\(\)\)\(\)\(\)\(\)\(\)\(\)\(\)\(\)\)\(\The number of tiers varies based on the complexity and level of detail needed for problem analysis. Typically, each tier contains no more than nine elements. The criteria within the criterion layer carry varying weights, which are determined using a scale from 1 to 9 and their reciprocals based on their significance in decision-making processes.