Liquefaction-proof design of houses: key insights and tools

ongoing

Soil liquefaction during earthquakes has been a problem of great concern in earthquake engineering for more than half a century. Yet, many small-scale structures, such as low-rise houses, are still designed without consideration of the effect of liquefaction and have thus suffered extensive damage in several recent earthquakes. Liquefaction mitigation measures involving pile foundations or extensive ground improvement are expensive solutions for residential properties underlain by deep liquefiable deposits. Such structures can be more efficiently designed with partial-depth ground improvement, i.e. allowing limited extent of liquefaction at larger depths. This idea is less costly and more sensible for residential buildings, but it requires reliable assessment of the liquefaction response to ensure that any induced deformations can be well-tolerated by the structure. Also, this assessment should consider the entire range of earthquake loads occurring during the life of the structure. The proposed project aims to provide the means for such a holistic assessment of the liquefaction performance of low-rise buildings. Specific emphasis will be placed on quantification of ejecta-induced damage resulting from a discharge of liquefied soils at the ground surface. This quantification will be based on an integration of insights and data from nonlinear dynamic analyses, seismic centrifuge tests, and case-history observations. A procedure for estimating ejecta-induced settlement will be developed and used alongside existing shear-induced settlement models within a novel framework for holistic evaluation of the liquefaction performance. The key objective of this framework is to guide the design process by providing an in-depth understanding of the characteristics of the liquefaction-building system response and the effect of ground improvement for different levels of shaking. The proposed project will contribute to improved physical and societal resilience to earthquakes.