New Insight in Liquefaction After Recent Earthquakes: Chile, New Zealand and Japan

Abstract

Liquefaction has proved to be one of the major geotechnical issues caused by earthquakes. It is one of the most costly phenomena and has afected several cities around the world. Although the topic has been studied since the 1960s, new questions are emerging. The earthquakes of Chile in 2010, New Zealand in 2010 and 2011, and Japan in 2011 had in common not only being some of the largest earthquakes of this decade but also having a problem of extensive liquefaction. Although most seismic codes have provisions against liquefaction, there are still some misconceptions regarding the characteristics of soil susceptibility and the efect of repeated liquefaction. This chapter introduces a detailed report of the damage caused by liquefaction in the cities afected by those earthquakes and also highlights observations in liqueied areas that were unexpected.Advanced geotechnical testing was conducted and compiled to compare them with previous assessment criteria and observations. A more comprehensive framework for the evaluation of liquefaction susceptibility and countermeasures will be presented and a roadmap of future work in the area will be described.

On the influence of cyclic preloadings on the liquefaction resistance of sands: A numerical study

“…Contrarily, samples that reached initial liquefaction and considerable accumulated axial strains such as 𝜀 1 = {7.5, 10}% (with 𝑟 𝑢 = 1) drastically reduced its liquefaction resistance. The aforementioned results are in agreement with former experiments using centrifuge tests [27,[27][28][29][30]73]. The results in the stress-strain space show a reduction in the axial strain accumulation during cyclic mobility on tests with undrained cyclic preloadings (i.e.…”

“…These preloadings greatly influence the subsequent soil mechanical behavior and liquefaction resistance [18][19][20][21][22][23][24][25][26]. For instance, seismic preshaking has a major effect on the subsequent liquefaction resistance of sands [27,[27][28][29][30]. The literature suggests that while a strong shaking event may lead to a reduction in the soil liquefaction resistance, a small shaking with partial or no liquefaction could greatly increase the liquefaction resistance [28,31,32].…”