## 2 Possible Failure Modes of the Slope
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Number** & **Source** & **Contribution** \\ \hline
6 & [11] & Research shows the validation of two methods of wedge stability analysis, namely, block theory and three-dimensional discontinuous deformation analysis (3D DDA), using physical models and field case histories. \\
7 & [12] & Simulations of real rockfall via discontinuous deformation analysis (DDA) are conducted. This novel technique properly considers the energy absorption ability of the slope based on vegetation conditions and the shape of rockfall and provides a new method for the assessment and preventive design of rockfall. \\
8 & [13] & The DDA method clearly shows the process of rock block failure and profoundly reveals the difference in sliding mode (caused by using different stability evaluation methods). \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Cont. Figure 4: Schematic diagram of slipping–buckling failure mode: (**a**) the slope is composed of a series of thin strata with interlayer shear zones in it; (**b**) the outer strata begin to slip in the upper part; (**c**) the slipping develops to the middle and bottom parts, and the bottom parts begin to buckle and extrude outward due to the great weight of the middle and upper parts acting on the limit width of the lower parts; (**d**) these deformation failure phenomena accumulate, ultimately causing a (**e**) collapse. Figure 5: Slipping along interlayer. Figure 6: Block failure. Hence, the possibility of rock failure, the above failure modes, and the deformation failure process, together with stability during excavation and long-term stability, are the key issues in slope excavation design. Through qualitative analyses and comprehensively considering the aspects of the geological characteristics of the three kinds of discontinuities, the features of the above three failure modes, and the possible scale of the failure strata, as well as the difference in the strike between the front and side slopes, one can ascertain that the slipping-bulking failure is more dangerous as it may cause strata failure from the top to the bottom of the slope [14; 15; 16; 17]. At the same time, this mode concerns the analysis of the deformation failure process, and the relevant studies regarding this type of failure mode are much more limited compared with the other two kinds of failure modes. [PERSON] et al. [6] analyzed the mechanical mechanism of buckling failure. In their study, a cusp catastrophe model was developed based on catastrophe theory and the formulations of the necessary and sufficient conditions for the instability of the slope were presented. [PERSON] et al. [18] analyzed the genetic mechanism of the buckling failure in a typical dip slope with a gentle gradient in the left flank of the Adige River valley south of Rovereto (North-Eastern Italy), as shown in Figure 7. In their study, this failure mode was back-analyzed using the Distinct Element Method (DEM) and Discontinuous Deformation Analysis (DDA). [PERSON] et al. [19] explored the mass source of the sturzstroms originating from prehistoric landslides and rock avalanches that occurred at the end of a glacial retreat in Vorarlberg, Austria. They believed that the sturzstroms were produced by a three-hing buckling failure that happened on the dip slopes due to alternating sandstone, marl, and conglomerate layers. In contrast with the above work, this article studies the deformation failure processes of buckling failure triggered by excavation and earthquakes in the Dabenliu quarry slope. This slope and its strata are higher and steeper than most of those in the literature. The effect of the reinforcement scheme will also b evaluated and refined accordingly. Many discontinuity-based methods, including DDA, DEM, the combination of FEM and DDA [20], and the coupled DDA-SPH method [21], were used to simulate the deformation failure processes of geological materials. Considering the possible features of deformation failure  
Figure 7: The buckling failure (from [PERSON] et al., 2009).