A comparative assessment of seismic soil liquefaction triggering relationships


Thesis Type: Postgraduate

Institution Of The Thesis: Orta Doğu Teknik Üniversitesi, Faculty of Engineering, Department of Civil Engineering, Turkey

Approval Date: 2015

Student: MAKBULE ILGAÇ

Supervisor: KEMAL ÖNDER ÇETİN

Abstract:

Starting with 1964 Niigata and Alaska Earthquakes, seismic soil liquefaction behavior has become a major research stream in geotechnical earthquake engineering. Since then, a number of investigators (e.g.: Seed et. al. (1984), Liao et. al. (1988, 1998), Toprak et. al. (1999), Cetin et. al. (2004) and Idriss and Boulanger (2004, 2008, 2012)) introduced deterministic and probabilistic liquefaction triggering assessment methodologies. The scope of this study is to develop an SPT-based seismic soil liquefaction triggering relationship on the basis of updated (2015) liquefaction triggering case history database and to assess the reasons behind the difference between CRR boundary curves recommended by Seed et. al. (1984), Cetin et. al. (2004), Idriss and Boulanger (2012) and this study. For this purpose, Cetin et. al. (2004) database is updated and extended with current state of knowledge. In the final database, there exist 211 case histories as compared to 200 case histories from Cetin et. al. (2004). A complete list of changes along with fully documented case history data is presented herein. Some changes in updated (2015) database as compared to (2004) version are applicable to every case history, for example more robust re-execution of rd and soil unit weights. On the other hand, some modifications are case history specific. On the basis of maximum likelihood theorem probabilistic CRR boundary curves are developed. These new boundary curves are used along with the curves of Seed et. al. (1984), Cetin et. al (2004) and Idriss and Boulanger (2012), for comparison purposes. Finally the source of difference between the proposed boundary curves by Seed et. al. (1984), Cetin et. al (2004) and Idriss and Boulanger (2012) is determined as i) differences in the selection of the critical layer and corresponding input parameters of SPT N and CSR values, ii) the execution of rd, K correction terms less importantly also due to MSF, fines correction and its limits, CN and its limits.