The performance of Karasu Bridge following the February 6, 2023 Kahramanmaras-Turkiye earthquake sequence

Abstract

The evaluation liquefaction-induced excessive ground displacements of the approach embankments of the Karasu Bridge, as surveyed following the Pazarcik M7.8 and Ekinozu-Elbistan M7.6, Kahramanmaras-Turkiye earthquakes on February 6, 2023, is presented. The Karasu Bridge, located on the Karasu River, connects the metropolitan city of Hatay and the State Hospital. The approach embankments of the bridge are underlain by layers of low to high plasticity stiff clay and liquefaction susceptible clayey and silty medium dense sand units. Specifically, the non-plastic silty sands with fines contents ranging from 21% to 42%, were evaluated as the critical (liquefied) soil units during the Pazarcik earthquake. Liquefaction triggering assessments, following the procedure outlined by Cetin et al. (2018), estimated factor of safety against liquefaction <1.0, confirming the surface manifestations of liquefaction at the site. Empirical approaches suggested by Hamada et al. (1986) and Youd et al. (2002) predicted lateral ground displacements triggered by liquefaction, averaging 137 cm and 383 cm, respectively. These values are comparable with mapped lateral displacements, which exceeded 150 cm. Volumetric settlement assessments, utilizing the method outlined by Cetin et al. (2009), predicted 14 to 26 cm, approximately one third to half of the mapped settlement values ranging from 40 to 55 cm. The discrepancy is attributed to the three-dimensional nature of site behavior and induced deviatoric strains, contributing to additional settlements beyond the volumetric component.