دانلود رایگان مقاله انگلیسی تجزیه و تحلیل عددی سیستم خاکی تحت روانکاری لرزه ای - الزویر 2018

Abstract

This study considers the motion of an end bearing single pile with lumped mass embedded in sandy soil deposit subjected to seismic liquefaction. An efficient finite difference model, whose accuracy was validated through experimental results, has been constructed to study the dynamic responses of piles under liquefaction. Effects of parameters such as soil and pile properties, and predominant frequency on dynamic response of pile are examined. Results reveal that earthquake predominant frequency, pile stiffness, soil relative density and soil-pile relative stiffness, can significantly affect the pile’s dynamic response, while pile material densities have negligible effects. Final results demonstrate that with increasing in pile stiffness, soil relative density and soil-pile relative stiffness, maximum moments in piles are increased while with increasing the earthquake predominant frequency, maximum moments in piles and depth of the liquefaction are reduced. Also, the depth in which the maximum value of moment, Mmax, occurs, depends only on the pile stiffness.

 Conclusions

Soil-pile interaction under seismic excitations has been considered in several numerical models and the influences regarding various effective parameters have been clarified. From observation and evaluation of 216 cases include 6 sections with different geometric characteristics and materials, soil with 3 various relative densities, and 4 earthquakes with predominant frequencies and maximum accelerations following conclusions have been drawn.

1. The depth of liquefaction of soil layer as well as the bending moment decrease with the increase of predominant earthquake frequency. This result is consistent with that obtained from previous findings [26]. The decrease of depth of liquefaction leads to the decrease of free length of pile.

2. In most (78.8%) of cases, increase in soil relative density increased the Mmax in pile, which shows the denser soil impose higher moment to the pile. This important point can render the conclusion that soils with higher relative densities that may provide a desirable situation in static design may increase the risk of bending failure in seismic loading conditions.