Dynamic soil-structure interaction analyses of two important structures affected by liquefaction during the Canterbury earthquake sequence

Abstract

The 2010–2011 Canterbury earthquake sequence produced significant damage in Christchurch. Much of the observed damage was related to soil liquefaction. The availability of building information, performance observations, survey data, geotechnical data, and ground motions recordings in Christchurch produced several well-documented case histories that provide insights to liquefaction-induced building settlement. Two case histories of important structures built atop fluvial soil deposits with sand and gravel layers are analyzed. One building was the third tallest building in Christchurch before the earthquakes, and the other building is an architectural landmark. Both structures were sited near the Avon River in zones of minor-to-moderate lateral spreading. Nonlinear dynamic soil-structure-interaction effective stress analyses are performed using the program FLAC with the PM4Sand constitutive model calibrated with laboratory tests or established simplified liquefaction procedures. The results show good agreement between observed and calculated responses of the ground and structure for the Canterbury earthquake sequence. Dynamic analysis identified several potential mechanisms contributing to the observed performance. Its use is encouraged to estimate shear-induced liquefaction building settlement.