Improving the capacity predictions of drilled displacement piles through the use of pile installation data-PPT Presentation

PPT Presentation

Pdf Summary

The presentation examines whether measurement-while-drilling (MWD) data can predict the axial capacity of drilled displacement piles (DDPs). MWD records installation variables such as depth, penetration rate, crowd force, rotation speed, and drilling pressure. These measurements can be combined into a cumulative installation-effort index, but a single overall index does not reliably predict pile capacity.<br /><br />Comparisons of three pile installations showed that similar cumulative effort can correspond to different axial capacities. Piles at the same site also displayed different installation effort and load-test results, while piles with comparable total effort could have different pile types and capacity behavior. This variability reflects differences in soil conditions and in how loads are carried through shaft friction versus end bearing.<br /><br />The study therefore decomposed total installation effort into shaft and toe components. This distinction improved capacity predictions for the piles examined: model estimates were close to measured test capacities for all three examples. The findings suggest that installation effort contains useful information about pile performance, but that aggregating it into one value obscures important load-transfer mechanisms.<br /><br />The authors conclude that MWD-based analytical prediction is promising, especially when shaft and toe contributions are treated separately. Future work should incorporate key geotechnical parameters and depth-specific MWD data to improve predictions of DDP axial behavior.

Keywords

measurement-while-drilling

MWD

drilled displacement piles

axial capacity

installation effort

shaft friction

end bearing

load transfer

pile capacity prediction

geotechnical parameters