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 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 about the possible efficiency of this strategy is quite limited. In this regard, the present study aims to evaluate the effectiveness of a vertical micropile system as a lateral spreading countermeasure using large-scale 1 g shake table tests on 3 x 3 pile groups. The results showed that the micropile system was not able to effectively reduce the bending moments in piles; however, it considerably reduced the lateral soil pressures exerted on the upslope piles of the group by the upper non-liquefiable layer. The employed micropiles restricted the lateral displacement of the upper non-liquefiable layer and, partially, that of the liquefiable layer, especially at upper depths. Several solutions were offered to enhance their performance including increasing the number of micropiles with a tighter pattern and using stiffer micropiles or fixing them in the underlying non-liquefiable layer. (C) 2022 Sharif University of Technology. All rights reserved.