It is well known that the bearing capacity of open-ended pipe piles used in port and harbor facilities depends on the so-called “soil plug”. On the other hand, previous model tests showed that tapered piles, in which the pile diameter gradually decreases toward the tip, can provide stable bearing capacity without relying on the plugging behavior, because the bearing capacity of the tapered pile is exhibited by the wedge effect of the tapered part. In this study, the difference in the bearing capacity between straight and tapered piles was analytically verified by using the Material Point Method (MPM) which is one of the particle methods. We simulates the penetration process of the pile into the ground and visualizes the stress state of the surrounding ground, the pile resistance (tip resistance, shaft resistance, etc.), and the distribution of frictional resistance on the pile. The analytical conditions is set up based on previous model tests and compares with those results. From the simulation results, it is confirmed that the bearing capacity of the tapered pile is larger than that of the straight pile when the plugging does not occur.

Key Words:MPM,open-ended pile,soil plug,tapered pile,bearing capacity