Effects of improper emergency mitigations on a large-scale landslide triggered by road excavation: A case study of the Fengping landslide, Hubei province, China

This study examines a large-scale landslide (5.15 x 10(6) m(3)) that occurred in Fengping village, Hubei Province, China. The landslide was triggered by road excavation but accelerated by improper emergency mitigations. Using finite element and limit equilibrium analysis, along with monitoring and experimental data, the evolution process and failure mechanism of Fengping landslide were studied. The findings reveal that the Fengping landslide was characterized by two sequential retrogressive movements, primarily driven by stress redistribution due to road excavation, rather than by rainfall or rise of groundwater. Precursor events, such as landslip movement and rockfalls, which occurred around the Fengping landslide toe, were misjudged as small-scale slope failures induced by heavy rainfall. The initial misinterpretation led to unsuitable emergency mitigations, such as unloading and slope cutting, which decreased the resisting force at the landslide toe and accelerated the landslide deformation up to 6.8 mm/day before treatment. The long-term reinforcement measures to the landslide, mainly including anti-slide piles and group rail piles, reduced the landslide deformation below 0.14 mm/day and improved the safety factor of the landslide to 1.23. This study underscores the necessity and importance of being alert and reducing human mistakes when performing initial emergency mitigations to landslides.