For open-ended pile foundations of port and harbor facilities, the design depending on the pullout resistance of piles does not tend to be adopted as rapid failure of structures is concerned. In order to construct and improve facilities more efficiently, proper evaluation of the pullout capacity is necessary. Although model tests are widely accepted to investigate the characteristics of piles in the ground, there are few such experiments focused on the pullout behavior for now. Therefore, in this research, model tests for pullout of piles are conducted by using a large soil tank (width of 6m; length of 3m; depth of 3m) and open-ended piles with diameter of 150mm and length of 3000mm.
In the experiments, we focus on the effect of installation process (penetration process into the ground) and shape of piles on pullout resistance. As the characteristics of pullout resistance would be changed by the deformation of the ground during the installation process, we prepare two kinds of piles that (1) do not disturb surrounding ground by placing in advance before setup of the ground and (2) penetrate into the ground for the installation process. For piles of (2), there are further two kinds of way such that static and dynamic penetration. For shape of piles, in addition to straight piles which are normally used in practice, tapered piles of which diameter decreases toward the tip are prepared. To investigate the difference of bearing capacity between these two shapes of piles, the static axial compressive load test and the lateral load test are also performed.
According to the results of these model tests, the pullout resistance is different depending on whether penetration process is performed or not. For example, the pullout resistance of the pile with penetration process is larger than that without penetration process. For the difference in characteristics of shapes of piles, the plugged effect is observed for the straight pile but not for the tapered pile.

Key Words: Pullout resistance, bearing capacity, tapered pile, penetration test, loading test,model test