Seismic effect on uplift bearing capacity of pile embedded in dry sand

Abstract

The growing rate of occurrence of earthquakes in Iraq and the whole region has driven to conduct this experimental research aiming at evaluating the uplift capacity of piles under seismic influence. Shaking table was especially manufactured to simulate the seismic loading resulting from Halabjah earthquake with high accuracy. Pullout tests were carried out on piles embedded in dry sand to determine the ultimate uplift load capacity before and after applying the seismic loading for different length to diameter ratios (L/D) of pile model 20, 25 and 30 and for loose and dense dry sand. It has been found that the maximum pull-out load of the pile after applying only Halabjah seismic loading was reduced between (8.16%) and (10.46%) in loose dry sand. However, there is no clear effect on tension pile capacity in dense dry sand except in pile of L/D=30, that bearing capacity increased by about 15.94%. And when apply combined loading of Halabjah seismic loading and uplift loading equal to one-third of maximum tension capacity the reduction of maximum pull-out capacity was between (55.02% to 73.22%) in loose sand while in dense sand there is a reduction about 50% for pile with L/D=20 and 25% and a low reduction of 8.06% for pile with L/D=30.