## 2 Common Destabilization Modes of Slopes with Soil-Rock Dichotomies  
The types of soil-rock binary structure slopes are complex and diverse. [PERSON] [2] compiled a substantial corpus of pertinent information and proposed a classification system based on criteria such as the morphology of the soil-rock contact surface, the properties of the soil-rock contact surface, the tendency of the top face of the slope, the thickness of the overlying soil layer, and the number of excavation steps in the overburden. The soil-rock binary structure slopes are categorized into the various types shown in Table 1. \begin{table}
\begin{tabular}{c c c} \hline
**Criteria for** & **Typology** & **Note** \\
**Classification** & & \\ \hline \multirow{4}{*}{Morphology of soil–rock contact surfaces} & Linear contact surface type & The shape of the soil–rock contact surface is straight \\  & Folded contact surface type & The shape of the soil–rock contact surface is folded \\  & Arc contact surface type & The shape of the soil–rock contact surface is curved \\  & Irregular contact surface type & Irregular shape of soil–rock contact surfaces \\  & Horizontal contact surface type & Approximate level of soil–rock contact surface \\  & Gently tilting contact surface type & Soil–rock contact surface angle \textless{} Integrated slope angle \\  & Properties of & Steeply inclined contact & Soil–rock contact surface angle \textgreater{} Integrated slope angle \\  & soil–rock contact & surface type & for slopes \\  & surfaces & Anti–dumping contact surface type & Soil–rock contact surface inclination is opposite to slope \\  & Oblique contact surface type & Soil–rock contact surface inclination at an angle to the slope inclination \\ \hline \end{tabular}
\end{table} 
Table 1: Types of slopes with soil–rock binary structures. However, it should be noted that some of these slope types are rare, and certain types of slopes (e.g., slopes with anti-dip yielding soil-rock contact surfaces and slopes with thin overlying soil layers) are not susceptible to slope instability. In light of the findings of [PERSON] et al. [5], the two most prevalent soil-rock binary structural slope types that are prone to destabilization, along with their associated destabilization modes and sliding surface patterns, are presented in Table 2.  
The first kind of soil-rock binary structure slope is characterized by a loose soil body piled up at the upper part and stable bedrock at the lower part. The strength parameters of the loose soil body and the soil-rock contact surface are significantly less than those of the bedrock, resulting in damage occurring primarily in the inner part of the loose soil body and at the soil-rock contact surface. The destabilization mode is primarily evidenced by rotational sliding within the loose-packed soil body and sliding of the packed soil body along the soil-rock contact surface. The sliding surface exhibits a composite morphology, comprising both a circular arc shape and a contact surface shape. The second soil-rock binary structure of the upper part of the slope consists of an accumulation of soil or fully weathered rock. The lower part is a rock body with a weak structural surface, which is characterized by a lower strength parameter than that of the upper part of the soil body and the soil-rock contact surface. For example, the parallel lines in the picture of the second type of slope structure in Table 2 represent the weak structural surface. Consequently, damage occurs not only within the soil body and at the