The use of cast-in-place concrete piles with enlarged base for increase the uplift resistance are known compared with straight piles. Initially, the angle of enlargement was 12 degrees, but with technological and constructional advances, this angle has increased up to 20 degrees. This report describes the results of uplift response of model piles in laboratory varying in shape and angle of enlarged base, N-value of soil and depth ratio of soil embedded. As the experiments results, the pullout resistance increases when the enlarged base is larger. In addition, the resistance increases exponentially with the increment of angle of enlargement.
