Model pile tests, using large calibration chamber in which the stress state and the relative density can be controlled, were performed in order to study the effect of soil condition on the behavior of open-ended steel pipe pile. The model pipe pile that was made up of two pipes to separately measure each component of bearing capacity of the open-ended steel pipe pile. Strain gauges were attached to study the load transfer characteristics of soil plug. The alteration of pile plugging was investigated with measurement of soil plug height during pile penetration.
Soil plug height, pile plugging, and driving resistance of the pile installed in sand were primarily dependent on the horizontal stress and the relative density. However, they were relatively unaffected by the vertical stress. Farthermore, the behavior of soil plug during penetration was quite different from the behavior in measureing the bearing capacity of pile(static load).
End bearing was primarily affected by the horizontal stress during the initial stage of installation, but as the penetration continue, it was gradually affected by the vertical stress more than the horizontal stress. Outside skin friction and total resistance were mainly dependent on the horizontal stress. End bearing, outside skin friction, and total resistance were also influenced by the relative density. Inside skin friction due to soil plug-pile interaction was larger than the bearing capacity of the soil at the toe, and most of the bottom bearing capacity of soil plug was developed in the bottom three diameter of soil plug. The horizontal stress at the pile-soil interation($\sigma_h$) became different from the original horizontal stress ($\sigma_h$).
