Kinetic characteristics and runout behavior of the rainfall-induced Hoengseong landslide at a solar power plant on 9 August 2022 in Gangwon Province, Korea

On 9 August 2022, the Hoengseong landslide was induced by heavy precipitation at a solar power plant in Gangwon Province, South Korea. The slope failed at the embankment of the solar power plant and subsequently transited to a high-mobilized debris flow. The fluidized mass, solar panels, and drainage components rushed down to National Route No. 6 and destroyed all vegetation along the valley. The debris mass killed one person and destroyed two houses. The Hoengseong landslide was initiated and had a long-runout distance of about 330 m, a total drop of 60 m, and a landslide volume of 1.5 x 10(4). This study presents to analyze the kinematic characteristics of a landslide-generated debris flow event with the PFC3D numerical model and linear contact bonding method. In order to analyze the distinctions between different processes, a combination of field surveys, unmanned aerial vehicle (UAV) photogrammetry, and laboratory triaxial tests were utilized. These methods were employed to extract essential parameters, including the digital elevation model and shear strength, which are associated with the rheological properties of landslide-debris flow materials. In dynamic analysis, the velocity, displacement, and characteristics of landslide deposition were considered. The results indicate that the initial landslide stage started with overall acceleration, and the movement of soil mass lasted approximately 1000 s with double-peak velocity curves and nonsynchronous displacement. Based on the simulation results, it was determined that the landslide had an average velocity of 0.848 m/s and a local maximum velocity of 3.138 m/s. It was observed that around 400 to 600 s into the simulation, two houses were demolished and underwent significant deformation. The morphology of the deposit exhibited a satisfactory agreement with the findings of the on-site survey. By offering comprehensive insights into the Hoengseong landslide, this study serves as a valuable resource for enhancing our comprehension of landslide dynamics and mitigating the risks associated with the potential reactivation of the Hoengseong landslide.

Automated summary

On August 9, 2022, a landslide occurred at a solar power plant in Gangwon Province, South Korea, due to heavy precipitation. This study analyzed the kinematic characteristics of the landslide-generated debris flow event using numerical modeling, aerial surveying, and laboratory tests. The results showed that the landslide had an average velocity of 0.848 m/s and a local maximum velocity of 3.138 m/s. The study provides valuable insights into landslide dynamics and can help mitigate the risks associated with similar events in the future.