Visualization of Plugging Phenomena in Vertically Loaded Open-Ended Piles: Fid-Bau Portal

Visualization of Plugging Phenomena in Vertically Loaded Open-Ended Piles

Kikuchi, Y. / Sato, T. / Morikawa, Y. / Kigata, K.

The objective of this study is to elucidate the mechanism of plugging phenomena at the tip of vertically loaded open-ended piles using the micro-focus X-ray CT scanner, which is a non-destructive examination method. A series of model tests were conducted to compare two pile shapes. The model piles used in this study were an open-ended pile and a close-ended pile. The behavior of the surrounding ground at the pile tip was discussed based on observation of the movement of iron particles extracted from visualized X-ray CT data. The CT images of the experimental results showed that the condition of wedge formation below the open-ended pile was clearly different from that below the close-ended pile. Although the penetration resistance of the open-ended pile and close-ended pile was similar, the movement of soil inside the open-ended pile was not stopped but was restricted, as shown by intermittent increases and decreases in penetration resistance during pile driving. The ground behavior was also observed based on concern about the phenomena in the open-ended pile due to changes in penetration resistance. In particular, it should be noted that the mechanism of the bearing capacity in open-ended piles is subtle, and may differ greatly from that in close-ended piles. Finally, knowledge of plugging phenomena was obtained by analyzing the distribution of the alteration of soil volume in X-ray CT images.