CPT Liquefaction Investigations, Adapazari, Turkey

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Liquefaction-induced building settlement and loss of bearing strength were major causes of damage during the 17 August 1999 Kocaeli, Turkey earthquake. The area primarily affected was within the city of Adapazari where hundreds of buildings settled and tipped by varying degrees due to liquefaction of subsurface sediment layers. With so many buildings affected, Adapazari provides a natural laboratory for the study of effects of liquefaction on building performance and development of improved design procedures to prevent future damage. Design of buildings to resist effects of liquefaction is a major issue in structural design in the US and other seismic areas. Because of the importance of this problem and the lack of adequate criteria in engineering practice, results from this study will likely be immediately and widely used in foundation design practice. Following the 17 August earthquake, NSF funded several reconnaissance investigations to Turkey, including a rapid deployment of an Earthquake Engineering Research Institute (EERI) reconnaissance team lead by the principal investigator (T.L. Youd) and follow-up geotechnical investigations organized through the Pacific Earthquake Engineering Research Center (PEER). These investigations produced a large and detailed inventory of settled and tipped buildings, the most extensive and complete inventory of such buildings following any earthquake to date. This building damage and the compiled inventory provide an important and unique opportunity to generate numerous documented case histories of building performance, complete with subsurface sediment stratigraphy and soil properties. These case histories are essential to the development of evaluation criteria and design procedures for prevention of liquefaction-induced building settlement and tilting due to liquefaction. The primary objective of this study is the compilation of stratigraphic cross sections and soil property data from an array of cone penetration soundings (CPT) to be conducted in areas of Adapazari most affected by building settlement and tilting. Soil samples will be extracted either by this project or through related projects for sediment classification and testing. A second major objective of this study is to prepare data files for distribution on the web and other venues for use by geotechnical and earth science professionals in the US and abroad. These data should be sufficient for analysts to develop and test procedures for predicting building settlement and loss of bearing strength at liquefaction-prone sites. A third objective will be to analyze the compiled data along with similar data from previous earthquakes to develop empirical procedures for evaluating building settlement and tilting hazard.