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Abstract
Soil liquefaction affects the maximum absolute bending moment acting
on piles during and after earthquakes. In this research, a numerical model
is prepared using the finite element program DIANA 9.3 (2008) in order
to investigate the behavior of piles in liquefiable soil during earthquakes.
The proposed model is able to represent the soil – structure interaction
system under seismic excitation and submerged conditions. A wide range
parametric study, considering submergence conditions, earthquake
magnitude, earthquake duration, pile diameter and pile length has been
carried out in order to investigate the behavior of such piles. Results
show that earthquake magnitude, pile diameter, pile length and
submerged conditions have major effects on the maximum absolute
bending moments. Results of full submergence case reflect the great
effect of soil liquefaction on increasing the bending moment acting on
pile, as a result of increasing the laterally transmitted loads. Moreover, it
is established that the loss of pile lateral supports due to soil liquefaction
causes an increase in the unsupported length of pile, hence the possibility
of lateral buckling. This behavior is obviously appears in cases of small
pile diameter. Additional models with liquefiable soil layer thickness
equal to 12 m have been carried out also, to investigate the location of
point of maximum bending moment.
The results show that the maximum
bending moments, act on pile, occurred at the boundaries between
liquefied and non-liquefied layers. Finally, recommendations for design
of piles in liquefiable soil under seismic excitation conditions have been
presented.