Misko Cubrinovski

Engineering Evaluation and Design for Liquefaction Hazards

As highlighted by the recently updated National Seismic Hazard Model, much of New Zealand is exposed to potential earthquake ground motions with moderate-to-high intensity. The Canterbury and Kaikōura earthquakes further demonstrated the country’s significant vulnerability to liquefaction hazards in both urban and rural environments. Ports, bridges, lifelines, and a substantial proportion of residential and commercial buildings are located in areas of high liquefaction potential. In order to protect these assets and the communities they support, it is necessary to directly (and more rigorously) consider liquefaction hazards in the engineering design.

This presentation focuses on a selection of commonly encountered challenges in the engineering evaluation of liquefaction effects on buildings, bridges, and land within New Zealand practice. Current design practices in relation to liquefaction hazards are critically reviewed and opportunities for their improvement are identified. The discussion covers the consideration of liquefaction effects in the design of shallow and deep foundations, including a recently developed methodology for estimating liquefaction-induced settlement for buildings on shallow foundations. Key aspects of kinematic loading, how to combine kinematic and inertial effects, and the importance of parametric scenario analyses for assessing liquefaction and lateral spreading are examined. Requirements for equivalent static analysis (incorporating liquefaction effects in a simplified manner) are highlighted. The presentation draws on well-documented case histories and findings from comprehensive research studies, and focusses on engineering assessment methodologies and their application in design practice.