The Role of Granular Cushion in Load Sharing of Unconnected Piled Rafts in Clayey Soils
Engineering and Technology Journal,
2021, Volume 39, Issue 12, Pages 1789-1796
AbstractOver 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
- 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.
 J. B. Burland, B. B. Broms, and V. F. B. de Mello, Behaviour of foundations and structures, Proc. Int. Conf. Soil Mech. Found. Eng. Tokyo, Japan. July 10-15, 1977, 2, 495–536, 1977.
 G. M. Zhuang and I. K. Lee, An elastic analysis of load distribution for raft-pile systems,Finite Elem. Anal. Des., 18, 1–3, 1994,259–272.doi: 10.1016/0168-874X(94)90106-6.
 M. Y. Fattah, M. J. Al-Mosawi, A. A. OO. Al-Zayadi, A. A. O., Time Dependent Behavior of Piled Raft Foundation in Clayey Soil, Geomechanics and Engineering, 5, 1, 2013,17-36 .
 M. Y. Fattah, M. J. Al-Mosawi, A. A. O. Al-Zayadi, Contribution to Long Term Performance of Piled Raft Foundation in Clayey Soil, International Journal of Civil Engineering and Technology (IJCIET), 5, 7, 2014, 130-148.
 X. D. Cao, I. H. Wong, and M.-F. Chang, Behavior of model rafts resting on pile-reinforced sand, J. Geotech. Geoenvironmental Eng., 130, 2, 2004, 129–138.
 I. H. Wong, M. F. Chang, and X. D. Cao, 17. Raft foundations with disconnected settlement-reducing piles, in Design applications of raft foundations, 469–486.
 F. Y. Liang, L. Z. Chen, and X. G. Shi, Numerical analysis of composite piled raft with cushion subjected to vertical load, Comput. Geotech., 30, 6,2003,443–453. doi: 10.1016/S0266-352X (03)00057-0.
 Y.-K. Seo, H.-J. Lee, and T.-H. Kim, Numerical analysis of piled-raft foundation considering sand cushion effects, 2006.
 A. Eslami and S. S. Malekshah, Analysis of non-connected piled raft foundations (NCPRF) with cushion by finite element method., Comput. Methods Civ. Eng., 2, 2, 2011.
 V. J. Sharma, S. A. Vasanvala, and C. H. Solanki, Behaviour of Cushioned Composite Piled Raft Foundation under Lateral Forces, Indian Geotech. J., 45, 1, 2015, DOI: 10.1007/s40098-014-0110-x.
 H. H. Karim, M. R. Al-Qaissy, M. K. Hameedi, Numerical Analysis of Piled Raft Foundation on Clayey Soil, Engineering and Technology Journal, 31, 7,Part A ,2013, 1297-1312.
 A. M. J. Alhassani and A. N. Aljorany, Parametric Study on Unconnected Piled Raft Foundation Using Numerical Modelling, J. Eng., 26, 5, 156–171, 2020. DOI: 10.31026/j.eng.2020.05.11.
 D. H. Hadi, M. Y. Fattah, M. Q. Whaheed, Effect of Number of Piles on the Behavior of Piled Raft Foundation , Engineering and Technology Journal, 39, Part A , 2021, (to be published).
 M. R. Mahmood, S. F. A. Al-Wakel, A. A. Hani, Experimental and Numerical Analysis of Piled Raft Foundation Embedded within Partially Saturated Soil , Engineering and Technology Journal, 35, 2, Part A , 2017 , 97—105.
- Article View: 229
- PDF Download: 190