Fragility functions for performance-based ground failure due to soil liquefaction

Abstract

The severity of liquefaction manifested at the ground surface is a pragmatic proxy of damage potential for various infrastructure assets, making it particularly useful for hazard mapping, land-use planning, and preliminary site-assessment. Towards this end, the recent Canterbury, New Zealand, earthquakes, in conjunction with others, have resulted in liquefaction case-history data of unprecedented quantity and quality, presenting a unique opportunity to rigorously develop fragility-functions for liquefaction-induced ground failure. Accordingly, this study analyzes nearly 10,000 liquefaction case studies from 23 global earthquakes to develop fragility functions for use in performance-based frameworks. The proposed functions express the probability of exceeding specific severities of liquefaction surface manifestation as a function of three different liquefaction damage measures (LDMs), wherein four alternative liquefaction-triggering models are used. These functions have the same functional form, such that end-users can easily select the model coefficients for the particular damage state, triggering model, and LDM of their choosing. It should be noted that these functions are not to be used to predict lateral spreading, which requires LDMs other than those assessed herein. Lastly, the proposed functions are preliminary and subject to further development. In this regard, several thrusts of ongoing investigation are discussed.