Recent rainfall- and excavation-induced bedding rockslide occurring on 22 October 2018 along the Jian-En expressway, Hub

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Haibing Yu I Changdong Li I Jia-Qing Zhou I Wenqiang Chen I Jingjing Long I Xutao Wang I Tao Peng

Recent rainfall- and excavation-induced bedding rockslide occurring on 22 October 2018 along the Jian-En expressway, Hubei, China

Abstract On 22 October 2018, at 17:20 (UTC+8), a bedding rockslide occurred on the right bank of the Jian-En expressway in Jianshi County, Hubei Province, Central China. Fortunately, a systematic displacement monitoring network provided an early warning. Thus, no casualties were caused by the rockslide, although two transport vehicles and three houses were damaged. To deduce the triggering factors and failure mechanism of the bedding rockslide, the geological characteristics, hydrogeological characteristics, slope excavation scheme, and rainfall data statistics were systematically investigated based upon field investigations, UAV photography, geological drilling, and laboratory tests. It was found that the bedding characteristics, presence of welldeveloped joints, and properties of the weak interlayers were the internal factors inducing the rockslide. The free face in front of the slope, the weak interlayer with low shear strength, and the through-going joint that formed the back boundary of slope constituted the boundary of the rockslide. The combined effects of improper slope excavation and concentrated rainfall were external factors that directly triggered the rockslide. The well-developed joints provided an effective infiltration channel for rainwater, and continuous rainfall deteriorated the shear strength of the weak interlayer ultimately causing the rockslide. Keywords Bedding rockslide . Failure mechanism . Triggering factor . Boundary condition . Displacement monitoring . Rainfall . Slope excavation Introduction Landslide geohazards are a persistent threat to human settlements and infrastructure worldwide. The failure mechanism of landslide has remained a long-term and investigated issue due to its complexity. The triggering mechanism for landslides is attributed to both internal and external factors. Regarding internal factors, some evidence has shown that weak interlayers are essential to the stability of slopes (Yin et al. 2011; Xu et al. 2013; Tang et al. 2015; Regmi et al. 2016; Zhao et al. 2016; Gu et al. 2017). Regarding external factors, rainfall and groundwater are the main natural factors triggering landslides (Toll 2001; Lee and Pradhan 2007; Staehli et al. 2015; Xu et al. 2015; Li et al. 2016; Lin et al. 2018; Cogan et al. 2018; Zhao et al. 2018; Yao et al. 2019; Tang et al. 2019; Zhou et al. 2019). In addition, many researches revealed that landslides are also related to human engineering activities (Cen et al. 2017; Ouyang et al. 2017; Xue et al. 2018; Zhao et al. 2019; Li et al. 2019). The study aims to explore the triggering factors of bedding rockslide recently occurring along the Jian-En expressway and to further reveal its failure mechanism. A systematic investigation was conducted including the slope excavation scheme, geological

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