Assessment of liquefaction potential in urban development areas of duzce province based on SPT data

This study aims to thoroughly evaluate the seismic liquefaction potential of soils within the urban development areas of Düzce province, Turkey. For this purpose, a total of 100 soil investigation reports obtained from the region were analyzed, focusing on Standard Penetration Test (SPT-N30) values, groundwater table (GWT) measurements, and fines content percentages passing the No. 200 sieve. Liquefaction assessments were conducted using the LiqIT v.4.7 software, based on the 1999 Düzce Earthquake parameters (magnitude and peak ground acceleration). The study calculated the factor of safety against liquefaction (FS), liquefaction potential index (LPI), and estimated post-liquefaction settlements. The findings indicate that the soils in the Düzce region exhibit a significant level of liquefaction risk. It was determined that the factor of safety (FS) value was below 1,0 in 96% of the analyzed parcels/plots, signifying a high potential for bearing capacity loss during an earthquake. Furthermore, in 75% of the boreholes, the liquefaction potential index (LPI) value exceeded the threshold of 15, which, according to Iwasaki et al. criteria, indicates a "very high" liquefaction potential. These data reveal that the risks of liquefaction-induced surface deformation and structural damage are considerable. The average calculated total settlement was 25,51 cm and settlements of 30 cm or more were observed 38% of the boreholes. In light of the study's findings, it is strongly recommended that effective ground improvement techniques and liquefaction-resilient structural design modifications be integrated into the project planning phases for current and future developments in Düzce province. This study provides a regional liquefaction assessment specific to Düzce, aiming to establish a solid engineering framework for future detailed analyses and risk mitigation strategies.