Evaluasi Risiko Likuifaksi Dengan Pendekatan Deterministik Dan Probabilistik Terhadap Penilaian Faktor Keamanan

Abstract

Liquefaction is one of the major issues in geotechnical engineering, particularly in earthquake-prone areas with loose sandy soils and high groundwater levels. Accurate assessment of liquefaction potential is essential to ensure the stability and safety of infrastructures. The deterministic method is widely used to evaluate the safety factor (SF) against liquefaction based on empirical correlations and fixed input parameters. However, this approach often fails to represent the natural variability and uncertainty in subsurface conditions and seismic loading.

This study aims to evaluate liquefaction risk using both deterministic and probabilistic approaches in the assessment of the safety factor. A case study was conducted in Babarsari, Sleman, Yogyakarta Special Region, using data from 16 borehole locations. The analysis was performed using the standard deterministic procedure, followed by a probabilistic analysis that incorporates parameter uncertainty through the Lind–Hasofer approach.

The results show a significant difference between the two approaches in terms of safety factor values and failure interpretation. The deterministic analysis yielded SF ≈ 1, corresponding to a reliability index of Ro ≈ 60% and a probability of failure Pf ≈ 40%. This indicates that the deterministic approach provides a simpler and more conservative estimate, whereas the probabilistic approach offers a more comprehensive, risk-based evaluation.

The comparison highlights the importance of integrating probabilistic methods into geotechnical practice, particularly for projects located in regions with high seismic hazard. Recommendations are provided regarding the selection of an appropriate approach based on project scale, data availability, and acceptable risk level.