Reusing existing displacement piles is economical, timesaving, and environment friendly. This paper presents an analytical approach for predicting the load carrying behavior of pile groups consisting of new and existing displacement piles. The evolutions of the undrained shear strength and shear modulus of clay adjacent to the piles from installation through consolidation to long-term ageing are investigated to determine the load carrying behavior of displacement piles. The nonlinear load-settlement behavior of an individual pile is modelled by load-transfer method, where the exponential function-based load-transfer models integrating the two developed soil parameters are employed to represent the nonlinear behavior at the pile-soil interface. The pile-pile interaction in the pile group is explored based on the shear displacement method. Combining the load-transfer method and the shear displacement method, an analytical framework is proposed for predicting the load-settlement behavior of pile groups consisting of new and existing piles. The proposed framework is validated by predicting the vertical settlement of a high-rise apartment built on a pile group consisting of 74 new displacement piles and 22 existing displacement piles during construction. Good agreement is achieved between the predicted and measured results. A parametric study is performed to explore the stiffness efficiency and the load-settlement behavior of pile groups with different layouts of new and existing piles. The results indicate that the pile group with larger ratio of the number of existing piles to the number of total piles shows both stronger stiffness and a higher load carrying capacity.


Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Ageing; Consolidation; Existing displacement pile; Stiffness efficiency

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Document Type

Article - Journal

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Final Version

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Publication Date

01 Oct 2019