Effectiveness of a vertical micropile system in mitigating the liquefaction-induced lateral spreading effects on pile foundations: 1 g large-scale shake table tests

Liquefaction-induced lateral spreading has caused severe damages to pile foundations during past earthquakes. Micropiles can be used as a mitigation strategy against lateral spreading effects on pile foundations. However, the available knowledge regarding the possible efficiency of such a strategy is quite limited. In this paper, the effectiveness of a vertical micropile system as a lateral spreading countermeasure was evaluated using large-scale 1g shake table tests on 3×3 pile groups. The results showed that the micropile system was not able to effectively reduce bending moments in piles while it reduced lateral soil pressures exerted on the upslope piles of the group by the upper nonliquefiable layer. The employed micropiles restricted lateral displacement of the upper non-liquefiable layer and partially that of the liquefiable layer, especially at upper depths. Solutions such as increasing the number of micropiles with a tighter pattern, using stiffer micropiles or fixing them in the underlying non-liquefiable layer can enhance their performance.