Abstract
A piled raft foundation is a combined foundation, which is developed to utilize the load-carrying capabilities of both raft and piles. To obtain an optimum piled raft design, it is important to properly evaluate and consider the load-sharing behavior between the raft and piles, which changes according to the settlement level of the piled raft. In this study, 27 three-dimensional finite element models were analyzed to investigate the piled raft coefficient with linear and nonlinear load-settlement behaviors. The length of piles was varied between 10, 15, and 20 m. The spacing between pile centers was varied between 3D, 5D, and 7D, and the pile diameter was kept constant. The number of piles and the distance between the exterior piles and the edge of the raft were maintained at 9 and 1 m, respectively. The sand conditions varied between dense, medium, and loose. The results indicated that the piled raft coefficient increases when the load-settlement curve is linear and decreases when the load-settlement curve is nonlinear. The influence of the incremental increase in pile length on the piled raft coefficient is more pronounced in short piles than in longer piles. The raft thickness has a negligible effect on the piled raft coefficient.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
ABAQUS (2011) User’s manual, version 6.11.3. Simulia
Achmus M, Kuo YS, Abdel-Rahman K (2009) Behavior of monopile foundations under cyclic lateral load. Comput Geotech 36:725–735
Budhu M (2008). Soil mechanics and foundation. Wiley.
Burland JB (1977). Behavior of foundations and structures on soft ground. In Proc. 9th ICSMFE (Vol. 2, pp. 495–546)
Comodromos E, Bareka S (2005) Evaluation of negative skin friction effects in pile foundations using 3D nonlinear analysis. Comput Geotech 32:210–221
Das B, Sobhan K (2013) Principles of geotechnical engineering. Cengage Learning.
El-Garhy B, Galil A, Youssef A-F, Raia MA (2013) Behavior of raft on settlement reducing piles: experimental model study. J Rock Mech Geotech Eng 5:389–399
Y. El-Mossallamy, Lutz B, TT Richter (2006) Innovative application of piled raft foundation to optimize the design of high-rise building and bridge foundation. In Proc. 10th Int. Conference on piling and deep foundation.
Horikoshi K, Randolph MF (1997) On the definition of raft–soil stiffness ratio. Géotechnique 47(5):1055–1061
Khoury M, Alzamora A, Ciancia A (2011) A piled-raft foundation for the tallest building. Geo-Frontiers 2011@ sAdvances in Geotechnical Engineering ASCE 3818–3827.
Lebeau J (2008) FE-analysis of piled and piled raft foundations. Graz University of Technology. Project Report
Lee J, Kim Y, Jeong S (2010) Three-dimensional analysis of bearing behavior of piled raft on soft clay. Comput Geotech 37:103–114
Lee J, Park D, Park D, Park K (2015) Estimation of load-sharing ratios for piled rafts in sands that includes interaction effects. Comput Geotech 63:306–314
Maharaj DK (2004) Three dimensional nonlinear finite element analysis to study the effect of raft and pile stiffness on the load-settlement behaviour of piled raft foundations. EJGE
Mandolini A, Di Laora R, Mascarucci Y (2013) Rational design of piled raft. Procedia Eng Comput Geotech 57:45–52
Patil JD, Vasanwala SA, Solanki CH (2014) An experimental investigation on behavior of piled raft foundation. Int J Geomat Geosci 5:300–311
Poulos H (2001) Method of analysis of piled raft foundation. A report prepared on behalf of Technical Committee TC18 on piled foundations. International Society of Soil Mechanics and Geotechnical Engineering
Rabiei M (2009) Parametric study for piled raft foundations. EJGE 14:1–11
Reul O, Randolph MF (2004) Design strategies for piled rafts subjected to nonuniform vertical loading. Geotech Geoenviron Eng 130:1–13
Sinha A (2013) 3-D modeling of piled raft foundation. University of Concordia.
Smith I M, and Griffiths DV (1997) Programming the finite element method. In soil-pile-structure effects on high rises under seismic shaking, by Nghiem HM, 102–162. ProQuest.
Acknowledgments
The authors would like to acknowledge the support provided by the Research Centre (RC) of College of Engineering and the Deanship of Scientific Research (DSR) at King Saud University.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Alshenawy, A.O., Alrefeai, T.O. & Alsanabani, N.M. Analysis of piled raft coefficient and load-settlement on sandy soil. Arab J Geosci 9, 475 (2016). https://doi.org/10.1007/s12517-016-2494-7
Received:
Accepted:
Published:
DOI: https://doi.org/10.1007/s12517-016-2494-7