Performance-based liquefaction hazard analysis and probabilistic liquefaction mapping

Presented by Alireza Javanbakht, Ph.D., Jacobs
Selecting a single combination of earthquake magnitude and maximum ground acceleration to evaluate liquefaction triggering in the Metro Vancouver region is challenging as the area is affected by multiple seismic sources. A probabilistic seismic hazard analysis based on the seismic hazard model of the 2020 NBCC is accomplished to account for all earthquake scenarios and consider the liquefaction model uncertainty and soil resistance variability. The liquefaction hazard curves are generated for the factor of safety against liquefaction and the amount of required soil improvement to prevent liquefaction which provide a comprehensive assessment of liquefaction triggering. The performance-based methodology offers a potential alternative to the conventional liquefaction analysis commonly employed by practicing engineers in BC. In addition, the liquefaction hazard curves from 900 CPT and shear wave velocity profiles are created by incorporating the liquefaction potential index (LPI) and Ishihara-inspired liquefaction potential index (LPIISH) into the performance-based liquefaction assessment. The first probabilistic liquefaction hazard maps of Metro Vancouver are presented using the targeted return periods of 475 and 2,475 years. The maps provide a preliminary evaluation for soil improvement applications.