# Flexural Buckling Failure of Rock Slopes: A Review of Influencing Factors and Analysis Methods
## 3 Deformation Process of Flexural Buckling Failure and Its Influencing Factors
### Factors Affecting the Deformation Process of Flexural Buckling
#### 3.2.2 Triggering Factors  
(1) Rainfall  
Rainfall, especially continuous heavy rainfall, could trigger buckling landslides. For example, in 2017, continuous rainfall in Xinmo, Sichuan, for as long as two months, resulted in the reactivation of old landslides in the Xinmo area, blocking the river for 2 km and burying more than 100 people [3]. The mechanism of rainfall affecting the stability of buckling landslides is mainly manifested in the following aspects. First, the rainfall-induced softening weakens the strength of the basal sliding surface, which significantly affects the buckling stability adversely. Second, the seepage field formed by rainfall infiltration generates static water pressure within the slope body, exerting a buoyant force and reducing the resisting force along the base of the sliding mass, thereby reducing the buckling stability. Finally, the rainfall infiltration will gradually reduce the matrix suction in unsaturated soil-like infillings or interbeds between layers, along which sliding occurs, which also leads to a reduction in buckling stability. The instability and failure of buckling landslides induced by rainfall is usually a relatively slow process, and current research mainly focuses on the impact of long-term heavy rainfall on buckling landslides investigated by using numerical methods, or the impact of static and dynamic water pressure formed by rainfall  
Figure 5: Variation of critical slope length with deformation modulus (data from [PERSON] et al. [48]). on buckling landslides through theoretical calculations. Due to the complicated mechanism of rainfall-induced buckling landslides, it remains a key and challenging issue in this research field. (2) Earthquakes  
Seismic landslides undergo the process of initiation, run-out, and accumulation in an extremely short period of time, releasing tremendous energy that often causes incalculable losses to the surrounding ecological environment and the safety of lives and property. The Tangjiashan coseismic landslide triggered by the Wenchuan earthquake in 2008 resulted in 84 deaths, and at the same time blocked the Jianjiang River to form a barrier lake, causing huge economic losses [47]. Under normal circumstances, the structural loosening of the slope body, the formation of internal fracture surfaces, and the sharp rise in pore water pressure within the slope body caused by earthquakes can create favorable conditions for the rapid initiation of buckling landslides. At present, the stability assessment of buckling landslides under earthquakes still poses a great challenge, and there is a relative scarcity of relevant research literature, which mainly focuses on theoretical analysis. Based on the principle of energy balance, [PERSON] et al. [47] proposed an analytical approach for evaluating the stability of buckling landslides considering the action of earthquakes and pore water pressure and verified the effectiveness of the developed analytical method with the Tangjiashan landslide case. By simplifying the seismic action as horizontal or vertical inertial forces using the pseudo-static method, [PERSON] et al. [52] derived analytical expressions for the stability assessment of dip slopes against flexural buckling and three hinge buckling under earthquakes and pointed out that the buckling instability of dip slopes is closely related to the direction of the horizontal seismic force. Utilizing the parameter sensitivity analysis method, [PERSON] et al. [53] investigated the impact of the horizontal seismic coefficient on the buckling stability of dip slopes, and the study showed that as the horizontal seismic coefficient increased, the critical buckling length decreased, and the buckling stability decreased. Recently, [PERSON] et al. [54] adopted a shaking table test to analyze the response of buckling landslides under continuous seismic loads, pointing out that the stress amplification of the bedding structure under earthquakes is an important reason for triggering buckling instability.