Using Pile Group to Mitigate Lateral Spreading in Uniform and Stratified Liquefiable Sand Strata: Three-dimensional Numerical Simulation

According to reports from past earthquakes around the world, the phenomenon of liquefaction is one of the main hazards of earthquakes that causes damage to structures and infrastructures. The risk of liquefaction and associated lateral spreading can be reduced by different ground improvement techniques, including the densification, solidification, vibro-compaction, drainage, explosive compaction, deep soil mixing, deep dynamic compaction, permeation grouting, jet grouting, pile-pinning and gravel drains or SCs. In this research, the effects of pile groups on reducing the potential for liquefaction during earthquakes are investigated parametrically, applying three-dimensional finite element (FE) simulations using OpenSees. Saturated Uniform and Stratified loose sand are subjected to two realistic destructive events with different characteristics. A multi-yield-surface plasticity model is considered for the dynamics analysis conducted in this study based on constitutive laws applicable to all types of soils. The objective of this study is to assess the effectiveness of the pile methods on the basis of several different factors, including area replacement ratio (Arr), piles diameter, number of piles, thickness and position of liquefiable soil, and earthquake characteristics. This parametric study evaluates the effect of each of these factors on soil acceleration, lateral displacement, and excess pore pressure. The results are shown, the responses of the saturated stratified sand strata are not only dependent on the thickness of the liquefiable layer but are also highly influenced by its position. The presence of a liquefiable layer at lower depths, although acting as an isolate relative to the acceleration, can increase lateral displacements.