계절별 지하수위 변동에 따른 2·3차원 액상화 위험도 특성 분석

초록

Liquefaction during earthquakes occurs when soil shear strength is reduced because of an increase in excess pore water pressure, resulting in severe geotechnical hazards such as differential settlement of structures and the uplift of underground facilities. Since the 2017 Pohang earthquake, accurate liquefaction hazard assessment has become increasingly important. However, conventional two-dimensional (2D) assessments often neglect seasonal groundwater fluctuations and cannot adequately characterize the depth-dependent distribution of liquefaction risk. To address these limitations, this study developed 2D liquefaction potential index maps and three-dimensional (3D) factor of safety voxel models by integrating 253 borehole datasets with seasonal groundwater levels for Q1 (dry season) and Q3 (wet season) estimated using Kriging and empirical Bayesian Kriging 3D. The results showed that liquefaction risk consistently increased during the wet season in both models. Notably, the high-risk area identified by the 2D assessment increased by 11.74 percentage points, substantially exceeding the 3.51% increase in high-risk volume observed in the 3D analysis. These findings suggest that 2D assessments may overestimate liquefaction risk because of their simplified weighting scheme. In contrast, the 3D analysis provides a more detailed evaluation of underground infrastructure by identifying depth-specific vulnerabilities. Therefore, integrating both approaches is recommended to improve liquefaction hazard assessment and risk management.

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