ASCE Geo-Institute/Seattle Section Geotechnical Group - September Meeting

Presentation: A new probabilistic common-origin approach to level-ground liquefaction susceptibility and triggering in all CPT-compatible soils using D_Q and its application in engineering design

Scott M. Olson, PhD, PE and Kevin W. Franke, PhD, PE

Zoom Link: https://us06web.zoom.us/j/88612944518

ABSTRACT

Based on a comprehensive database involving 401 cases of observed liquefaction (or no liquefaction), the authors developed a new probabilistic procedure to simultaneously assess liquefaction susceptibility and triggering for nearly all CPT-compatible soils ranging from non-sensitive clays to clean sands. This procedure has several advantages, including (1) it eliminates the need for a fines content adjustment; (2) it identifies a threshold for fine-grained soils that are not susceptible to liquefaction and large strength loss; and (3) it differentiates the liquefaction resistance of clean sands with differing mineralogy and compressibility, as reflected in CPT parameters. At the same time, based in part on conversations with numerous practitioners, the authors have identified two troubling trends in probabilistic liquefaction triggering analyses. Firstly, many engineers employ only model uncertainty in probabilistic liquefaction triggering analyses, which may significantly underestimate the total uncertainty involved in an analysis. Secondly, many engineers apply a factor of safety “buffer” to deterministic liquefaction triggering curves defined from probabilistic studies. This combination may result in significant (over)conservativism in a triggering analysis. When considered jointly with all the conditional probabilities associated with unacceptable liquefaction hazard (e.g., ground motions, triggering, and consequences), it appears that we, as a profession, often over-predict the actual risks from liquefaction-related effects.

 BIOGRAPHIES

SCOTT M. OLSON, PhD, PE

Scott M. Olson, PhD, PE is a Professor and Faculty Excellence Scholar in the CEE Department at the University of Illinois, where he joined the faculty in 2004. Prior to joining Illinois, Scott worked in practice for Woodward-Clyde Consultants and URS Corporation. Prof. Olson has researched static and seismic liquefaction for over 25 years, and has been involved in dozens of research and consulting projects involving geotechnical earthquake engineering; tailings dam engineering; in situ, laboratory, and centrifuge testing, soil-foundation-structure interaction; and paleoliquefaction and geohazards analysis. From these activities, Scott has published nearly 150 journal papers, conference articles, and reports, and has received numerous awards, including the ASCE Walter L. Huber Civil Engineering Research Prize and the Canadian Geotechnical Society R.M. Quigley Award. Prof. Olson serves in various capacities for the Geo-Institute, USUCGER, EERI, and the Transportation Research Board (TRB). And recently, he became a founding member of the U.S.-based Tailings and Industrial Waste Engineering (TAILENG) Center.

KEVIN W. FRANKE, PhD, PE

Kevin W. Franke, PhD, PE is an Associate Professor in the Department of Civil and Environmental Engineering at Brigham Young University, where he joined the faculty in 2012. Kevin’s principal research focus relates to geotechnical/earthquake engineering, performance-based methods for dealing with soil liquefaction and its associated hazards, and autonomous applications of unmanned aerial vehicles (UAVs) in monitoring infrastructure and performing post-disaster reconnaissance. He serves as a Co-Principal Investigator in the NSF-sponsored Center for Unmanned Aircraft Systems (CUAS), a Steering Committee member of the Geotechnical Extreme Events Reconnaissance Association (GEER), Vice Chair of the Earthquake Engineering and Soil Dynamics Committee of the ASCE Geo-Institute, and member of the U.S.-based Tailings and Industrial Waste Engineering (TAILENG) Center. Since 2012, Kevin has published more than 70 peer-reviewed journal papers and conference articles. Prior to his current academic position, Kevin worked for 6 years as a professional engineer for Kleinfelder, Inc. and URS Corporation.