| چکیده انگلیسی مقاله |
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 various ground improvement techniques, including densification, solidification (e.g., cementation), 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, using three-dimensional finite element (FE) simulations via OpenSees. Saturated uniform and stratified loose sand are subjected to two realistic destructive events with different characteristics. A multi-yield-surface plasticity model, Drucker–Prager yield criterion, is considered for the dynamic analysis conducted in this study based on constitutive laws applicable to all types of soils. The objective of this research is to assess the effectiveness of the pile group based on several different factors, including area replacement ratio ( ), 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 showed that the lateral displacement and excess pore pressure decrease, as the area replacement ratio, number, and diameter of the pile increase. Besides, 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. Also, according to the results, there is an appropriate correlation between the variations of lateral displacement rate of piles and soil and earthquake parameters including Arias intensity, the time corresponding to the PGA, and the number of significant excitation cycles. Therefore, the results of this study may be applicable for other earthquakes. |