The Role of Granular Cushion in Load Sharing of Unconnected Piled Rafts in Clayey Soils

Khalifa, Karam R.; Fattah, Mohammed Y.; Salim, Nahla M.

doi:10.30684/etj.v39i12.2076

	The Role of Granular Cushion in Load Sharing of Unconnected Piled Rafts in Clayey Soils
Engineering and Technology Journal
Article 7, Volume 39, Issue 12, December 2021, Pages 1789-1796 PDF (988.61 K)
Document Type: Research Paper
DOI: 10.30684/etj.v39i12.2076
Authors
Karam R. Khalifa^* ; Mohammed Y. Fattah; Nahla M. Salim
Civil Engineering Dept., University of Technology-Iraq, Alsina’a street, 10066 Baghdad, Iraq.
Abstract
Over the past few decades, interest has grown about the role of the piled raft structure in soils. A structural fill cushion separates the piles from the raft in the form of an unconnected piled raft base (UCPRF). Given the advantage of this structure, the load is dispersed between the raft and the piles by the cushion. The cushion serves as a load redistributor between the raft and the piles. Load dispersion capability of the system was theoretically estimated using PLAXIS finite element analysis software in this study. The effect of cushion thickness on settlement reductions was investigated as well. Obtained results showed that the pile head has the greatest axial stress in the piled raft system., however decreased along the length of the pile according to finite element analysis. The unconnected head's maximum axial load is transferred down to a point a certain distance below the pile head (approximately two meters in the studied model). Above the top two meters, the axial stress in the pile begins to decrease, following the same pattern as the connected system. The thickness of the cushion affects the load sharing between the cushion and the piles. As the cushion thickness increases, the axial stress at the pile head decreases
Highlights
The load sharing capability of the system was investigated using PLAXIS finite element analysis. The impact of cushion thickness on settlement reductions was investigated. The pile head has the greatest axial stress in the connecting piled raft system., and then decreases along the length. The unconnected head's maximum axial load is transferred down to a point a certain distance below the pile head. As the cushion layer thickness increases, the axial stress at the pile head decreases.
Keywords
Piled raft; Cushion; Disconnected; Soft clay; Finite elements

References
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