Seismically induced settlement of buildings with shallow foundations on liquefiable soils has resulted in significant damage in recent earthquakes. Engineers still largely estimate seismic building settlement using procedures developed to calculate postliquefaction reconsolidation settlement in the free-field. A series of centrifuge experiments involving buildings situated atop a layered soil deposit have been performed to identify the mechanisms involved in liquefaction-induced building settlement. Previous studies of this problem have identified important factors including shaking intensity, the liquefiable soil's relative density and thickness, and the building's weight and width. Centrifuge test results indicate that building settlement is not proportional to the thickness of the liquefiable layer and that most of this settlement occurs during earthquake strong shaking. Building-induced shear deformations combined with localized volumetric strains during partially drained cyclic loading are the dominant mechanisms. The development of high excess pore pressures, localized drainage in response to the high transient hydraulic gradients, and earthquake-induced ratcheting of the buildings into the softened soil are important effects that should be captured in design procedures that estimate liquefaction-induced building settlement.

The effective application of liquefaction mitigation techniques requires an improved understanding of the development and consequences of liquefaction. Centrifuge experiments were performed to study the dominant mechanisms of seismically induced settlement of buildings with rigid mat foundations on thin deposits of liquefiable sand. The relative importance of key settlement mechanisms was evaluated by using mitigation techniques to minimize some of their respective contributions. The relative importance of settlement mechanisms was shown to depend on the characteristics of the earthquake motion, liquefiable soil, and building. The initiation, rate, and amount of liquefaction-induced building settlement depended greatly on the rate of ground shaking. Engineering design procedures should incorporate this important feature of earthquake shaking, which may be represented by the time rate of Arias intensity ͑i.e., the shaking intensity rate͒. In these experiments, installation of an independent, in-ground, perimetrical, stiff structural wall minimized deviatoric soil deformations under the building and reduced total building settlements by approximately 50%. Use of a flexible impermeable barrier that inhibited horizontal water flow without preventing shear deformation also reduced permanent building settlements but less significantly.

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This paper presents a predictive model for the settlement of shallow-founded structures on liquefiable ground during earthquakes. The model is based on the results of an extensive fully coupled, three-dimensional numerical parametric study of soil–structure systems, validated with centrifuge experiments as well as a database of case history observations. The results of the numerical study provided insight into the relative importance and influence of each input parameter and the functional form of the predictive model for a structure's permanent settlement. The case history database helped validate and refine the predictive model, accounting for complexities of the ground motion and site conditions in the field. Non-linear regression and latent variable analysis were used to develop model coefficients. The uncertainty around model estimates was modelled by a lognormal distribution. An additional logistic model was provided to estimate the probability of insignificant settlement (defined as less than 1 cm). The proposed probabilistic procedure considers variations in site conditions as well as the presence and properties of a building in three dimensions. By including the case history database in its validation and adjustment, the model captures all mechanisms of settlement below the foundation, including volumetric and deviatoric strains as well as ejecta. The total uncertainty around its predictions is rigorously characterised, which is a necessary step before the benefits of performance-based seismic design can be realised in the evaluation and mitigation of the liquefaction hazard.