Analysis of Features of Long and Short Pile Composite Foundation in High-Rise Buildings: Fid-Bau Portal

Analysis of Features of Long and Short Pile Composite Foundation in High-Rise Buildings

Yang, Yong / Zhang, Jichao

This study analyzed the mechanical mechanism of long-short-pile composite foundations under the interaction between the superstructure and foundation using the finite element method, field test data, and the standard formula calculation method. More specifically, the influences of the long-short-pile composite foundation on the axial force and side friction resistance of the long pile were analyzed, including the cushion thickness, pile length, and raft thickness. The results indicate that laying the cushion changes the stress mechanism of the pile, slows the stress concentration of the pile top, and adjusts the load-sharing ratio of long and short piles, which contributes to the total function of the pile stress and decreases the wear of the foundation. The bearing of the long-short-pile composite foundation is improved by increasing the long pile length. However, when the length of the long pile is increased to a certain limit, the bearing capacity of the foundation is not substantially improved. An excessive increase in pile length will cause material wastage and increase the engineering cost. The increase in the raft thickness slows the stress concentration at the long pile’s top. In that design, the thickness of the raft can be increased to avoid damage to the pile top due to excessive stress. The results of this study serve as a reference for optimal designing of the cushion thickness, pile length, and raft thickness in this type of foundation.