The effect of underground columns on the mitigation of liquefaction in shaking table model experiments (original) (raw)

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 non-liquefiable 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 ...

The present study attempts to develop a new method for dissipation of excess pore water by installation of new type of prefabricated drains so called micro drains. The main advantages of this type of drain in respect to the traditionally used are their fast and simple installation, faster dissipation of pore pressures, possibility of application on existing structures, installation in conditions of limited space for manipulation, possibility of additional intervention to prevent clogging of the drain, etc. Investigations that have been performed within the frames of this project explored micro drains as mitigation measure against liquefaction. Series of shaking table tests were performed to investigate the efficiency of new type of drains. The results from these investigations confirm the high performance of micro drains as one of the most efficient measures against liquefaction.

Pile foundations are relatively vulnerable to lateral loads. During liquefaction-induced lateral spreading, this vulnerability is particularly conspicuous due to a loss of strength and stiffness in the liquefied soil. A nonlinear effective stress analysis incorporating an elastoplastic constitutive model based on Finite Difference Method (FLAC2D program) was used to numerically simulate shake table experiment on piles in laterally spreading soils. The soil-pile interaction has been properly considered by using interface elements. The main objective of this paper is to assess the accuracy of a 2D numerical simulation of physical models in predicting the dynamic response of pile foundations and to identify the capability of 2D numerical simulation for 3D effects such as shadow and neighboring effects in pile groups without a pile cap. Results are presented and discussed, in which the obtained response from the simulation is compared to that measured in the test. For the single pile, a...