Effect of Soil Relative Density on the Seismic Behavior of the Pile in Liquefiable Soil

Buildings and bridges on loose to medium dense sands are often built on piles foundation. If sand layer is saturated, liquefaction is likely to occur. In recent earthquakes, liquefaction and its effects have been reported as one of the main reasons for failure of piles and pile-supported structures [1]. When pile foundations are exposed to intense dynamic transverse loads during earthquakes, soil–structure interaction (SSI) plays an important role in allocating the response of pile foundations to lateral excitation [2]. Recent observations after major earthquakes have shown that extensive damages and destructions are still likely to be happened to pile foundations. This problem is significant particularly for pile foundations in loose saturated cohesionless deposits which are vulnerable to liquefaction and lateral spreading during seismic loading. Design procedures that have been developed for evaluating pile behavior under earthquake loading, have many uncertainties to be used for cases involving liquefaction. The performance of piles in liquefied soil layers is much more complex than that of non-liquefying soil layer as a result of the diminishing of stiffness and shear strength of the surrounding soil over time due to the increase of pore water pressure [3].By increasing the density of the soil the probability of liquefaction is reduced liquefaction. Soil compaction increases the soil relative density, modulus of elasticity, the angle of internal friction, and SPT-N of the soil. With regard to the relationships in soil mechanics science increase of relative density causes the bearing capacity of foundation to be increased, improves the soil properties, reduces the inappropriate subsidence, risk of liquefaction, and stabilizes embankments. High relative density is accounted suitable for geotechnical activities and provides the ideal conditions at least for static designs.