Investigation into the Settlement of a Case Study Building on Liquefiable Soil in Adapazari, Turkey

Abstract

This paper investigates the key parameters that influenced the settlement of a case study building on liquefiable soil in Adapazari (Turkey) during the 1999 Kocaeli earthquake. Ground movements in Adapazari caused large devastation, largely attributed to liquefaction of low plasticity silty soil layers underneath buildings on shallow foundations. The case study soil profile was well characterized by in-situ testing as well as laboratory tests from the Adapazari area. This allowed several different estimates of the building settlement to be obtained through different methods and through a variation in upper and lower bound estimates of the soil parameters. The different methods and different soil properties resulted in a wide range of estimates from 0.004 m to 1.6 m for the building settlement, compared to the observed in-situ value of 0.9 m. Even though the results were varied, the estimation of the liquefied strength of the soil appeared to be a key parameter for the settlement of the case study building. A detailed study with the PLAXIS finite-lement software and UBC3D-PLM constitutive model, provided a consistent estimate of the final settlement of 0.9 m compared to the in-situ value. However, the limitation due to the enforced 'undrained' conditions during the dynamic phase of the analyses may have resulted in an inaccurate simulation of the pore water pressure and subsequently could have influenced the estimation of settlement. The modeling of the liquefaction settlements under free-field conditions was also considerably less than the re-consolidation settlements that were obtained through simplified procedures, suggesting that the re-consolidation settlement under the foundation was not modelled accurately. The present paper focuses on the assessment of the settlements due to earthquake-induced liquefaction as part of the research being conducted within the European project LIQUEFACT.