Laboratory testing procedure to assess post-liquefaction deformation potential

Abstract

Buildings and infrastructure suffer extensive damage due to liquefaction during strong earthquakes. The FL method has long been considered adequate for evaluating the likelihood of liquefaction, and is widely used. Due to the high frequency of large earthquakes, generally referred to as level 2 earthquakes, the necessity of multi-level assessments has been acutely felt in Japan. This requires the ductility nature of liquefied ground to be assessed. Because these earthquakes do not always occur with the motion level and waveform used in design, new assessment methods are required which take some deviation into account. Another point of consideration in developing a new method is that high quality site investigations are often either not possible or practical in the initial stage of design. Because the site investigation methods should differ depending on the site selection and the precise design of important structures, there is a clear demand for assessment methods with the flexibility to meet the particular objectives of each case. The new laboratory testing procedure proposed in this paper aims to classify soils according to their likelihood to undergo liquefaction in the event of an earthquake. With the proposed procedure, it is possible to classify soils as either ‘clearly safe’ or ‘likely to result in significant damage if liquefied’ by testing a small number of specimens. It should be noted that this test is not designed to provide for a highly accurate prediction of liquefaction or the extent of post-liquefaction deformation.