Journal of the Korean Geo-Environmental Society ISSN:1598-0820(Print) 2714-1233(Online) 한국지반환경공학회 논문집

Due to climate change, the frequency and intensity of localized heavy rainfall events have increased, leading to a rise in ground failure incidents. In such cases, groundwater level rise caused by rainfall is a major factor influencing ground stability. This study quantitatively analyzes the correlation between rainfall-induced groundwater level rise and ground stability based on an actual ground failure case. Field data collected from installed groundwater level gauges were utilized, and back analysis was conducted using data from 2024, when the ground was considered stable, in order to estimate the soil properties (permeability coefficients). Numerical analysis was performed using the commercial geotechnical software Plaxis-2D. The results of the back analysis showed an average error rate of 0.19% between the calculated and measured groundwater levels for each section, indicating that the estimated permeability coefficients were reliable and applicable to the conditions at the time of failure. Based on these properties, additional numerical analyses were conducted to assess groundwater level rise at the time of failure. The results showed that although the maximum daily rainfall during the 2024 analysis period was higher than that during the 2023 failure event, the cumulative three-day rainfall was greater in 2023. Consequently, the average groundwater level rise at the time of failure was 0.88 m, compared to 0.49 m during the peak rainfall in 2024. These findings indicate that cumulative rainfall, rather than single-day intensity, has a more significant impact on groundwater level rise, and that rapid increases in groundwater level can lead to ground instability.