The National Academies of Science, Engineering & Medicine (NASEM) recently released a report of high value for the engineering community on the "State of the Art and Practice in the Assessment of Earthquake-Induced Soil Liquefaction and Its Consequences". The report aims to help the technical community reach again consensus on issues related to liquefaction triggering assessment and build confidence in methods used to assess liquefaction initiation and its consequences.
The report focuses on developments since the 1996 and 1998 National Science Foundation/National Center for Earthquake Engineering Research (NCEER) workshops, where consensus was last reached on the topic of assessing liquefaction triggering. A committee of 12 engineers and scientists thoroughly evaluates the following: the sufficiency, quality, and uncertainties associated with laboratory and in situ field tests, case history data, and physical model tests for understanding liquefaction triggering and post-triggering soil behavior; methods to analyze the data from those tests; and the adequacy and accuracy of empirical and mechanistic methods to evaluate triggering and resulting deformations in the soil and the structures built in, on, and of those soils. The report considers future directions for research and practice, coming with a number of recommendations in the end.
In a brief overview, the report deals with the following:
- Provides a description of the phenomena associated with earthquake - induced soil liquefaction and the factors influencing them;
- Discusses the sufficiency of the case history data on liquefaction and associated phenomena, including field case histories, and provides a critical assessment of those data;
- Describes and assesses the simplified stress - based approach to predict the initiation of liquefaction;
- Assesses alternative approaches to liquefaction triggering assessment such as strain - based, energy - based, and computational mechanics - based approaches;
- Describes the assessment of the post - liquefaction shear strength of soils;
- Discusses empirical and semi - empirical methods to evaluate liquefaction consequences;
- Discusses how computational mechanics can be used to predict liquefaction triggering and consequences;
- Discusses performance - based engineering methods for probabilistic evaluation of liquefaction susceptibility, triggering, and consequences;
- Provides committee recommendations for advancing the state of practice and state of the art for assessment of earthquake - induced soil liquefaction.
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