Numerical Simulation of Drive-Drill-Drive Techniques for Open-Ended Pile Installations

Pile penetration refusal in difficult soils has been a subject of concern. In recent past, the Drive-Drill-Drive technique has been deployed to facilitate the penetration of open-ended piles after refusal. In this technique, the soil inside the pile is drilled using regular drilling tools that once the pile reaches a refusal state. The drilled material is then pulled out of the pile. The reduced internal friction then facilitates the further penetration of the pile. The removal of the drilled soil also causes stress state changes both within and outside the pile. The work plans to study the changes in the stress state of the soil outside the pile due to the drilling and removal of soil. The work studies the effect of this installation process on end bearing resistance and vertical bearing capacity of the open-ended pile. Numerical FE model using a hypoplastic soil constitutive model was developed to simulate the installation process. The results were compared to results obtained from commercial software GRLWEAP. Unlike, observations made on field, the final end bearing resistance of the pile as per the simulation results was found to be around 65% of the value estimated by the GRLWEAP without any soil removal. Four driving variations with different driving depths and diameters were studied.

Schlagworte

ABAQUS/explicit

Drive-Drill-Drive

Hypoplastic model

Offshore wind

Pile refusal

Zipper technique

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Numerical Simulation of Drive-Drill-Drive Techniques for Open-Ended Pile Installations