Abstract
Over the past two decades, a number of researchers studied different aspects of the unconnected piled raft foundation (UPRF) system. In this system, a structural fill cushion is inserted between the raft and the concrete piles (PC) where the cushion transfers the loads from the superstructure to the piles. They showed that UPRF could increase the load-bearing share of the raft relative to that of the concrete piles, which leads to a favourable economic impact. Stone columns (SC) and deep-mixed columns (DMC) have also gained substantial popularity in the last few decades, and have shown pronounced success in substituting concrete pile foundations in numerous projects. This paper is an attempt to explore the viability of using SC and DMC in the UPRF system. Different column parameters such as material, stiffness, spacing, embedment length, configuration and raft thickness may affect the design considerations of UPRF systems. The current study investigates the effect of such parameters on the performance of the UPRF. In addition, two cushion alternatives were also studied: structural fill and EPS Geofoam. 3D finite element models of a 16-storey building on soft clay were used to compare the behaviour of different types of UPRF foundations embedded in different types of soft clays. A coupled hydraulic and mechanical model using the Modified Cam Clay soil model was used to model the soft soil.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Abdelrahman GE, El Kamash WH (2014) Behavior improvement of raft foundation on port-said soft clay utilizing geofoam. Geo-Shanghai 2014, May 26–28, Shanghai, China, 557–566, DOI: https://doi.org/10.1061/9780784413401.055
Alnuaim A, El Naggar H, El Naggar MH (2015a) Performance of micropiled raft in sand subjected to vertical concentrated load: Centrifuge modeling. Canadian Geotechnical Journal 52(1):33–45, DOI: https://doi.org/10.1139/cgj-2014-0448
Alnuaim A, El Naggar MH, El Naggar H (2015b) Performance of micropiled raft in clay subjected to vertical concentrated load: Centrifuge modeling. Canadian Geotechnical Journal 52(12):2017–2029, DOI: https://doi.org/10.1139/cgj-2014-0001
Alnuaim AM, El Naggar MH, El Naggar H (2016) Numerical investigation of the performance of micropiled rafts in sand. Computers and Geotechnics 77:91–105, DOI: https://doi.org/10.1016/j.compgeo.2016.04.002
Alnuaim AM, El Naggar MH, El Naggar H (2018) Performance of micropiled rafts in clay: Numerical investigation. Computers and Geotechnics 99:42–54, DOI: https://doi.org/10.1016/j.compgeo.2018.02.020
Ata A, Badrawi E, Nabil M (2015) Numerical analysis of unconnected piled raft with cushion. Ain Shams Engineering Journal 6(2):421–428, DOI: https://doi.org/10.1016/j.asej.2014.11.002
Budhu M (2007) Soil mechanics and foundations, 2nd edition. John Wiley & Sons, Inc., Hoboken, NJ, USA
Cao XD, Wong IH, Chang MF (2004) Behavior of model rafts resting on pile-reinforced sand. Journal of Geotechnical and Geoenvironmental Engineering 130(2):129–138, DOI: https://doi.org/10.1061/(ASCE)1090-0241(2004)130:2(129)
El Kamash W, El Naggar H (2018) Numerical study on buckling of end-bearing piles in soft soil subjected to axial loads. Journal of Geotechnical and Geological Engineering 36(5):3183–3201, DOI: https://doi.org/10.1007/s10706-018-0529-4
El Kamash W, Han J (2014) Displacements of column-supported embankments over soft clay after widening considering soil consolidation and column layout: Numerical analysis. Soils and Foundations 54(6):1054–1069, DOI: https://doi.org/10.1016/j.sandf.2014.11.002
El Kamash W, Han J (2017) Numerical Analysis of Existing Foundations underpinned by Micropiles. ASCE International Journal of Geomechanics 17(6), DOI: https://doi.org/10.1061/(ASCE)GM.1943-5622.0000833
El Sawwaf M (2010) Experimental study of eccentrically loaded raft with connected and unconnected short piles. Journal of Geotechnical and Geoenvironmental Engineering 136(10):1394–1402, DOI: https://doi.org/10.1061/(ASCE)GT.1943-5606.0000341
Fioravante V (2011) Load transfer from a raft to a pile with an interposed layer. Geotechnique 61(2):121–132, DOI: https://doi.org/10.1680/geot.7.00187
Horikoshi K, Matsumoto T, Hashizume Y, Watanabe T, Fukuyama H (2003) Performance of piled raft foundations subjected to static horizontal loads. International Journal of Physical Modelling in Geotechnics 3(2):37–50, DOI: https://doi.org/10.1680/ijpmg.2003.030204
Kulhawy FH, Mayne PW (1990) Manual on estimating soil properties for foundation design. No. EPRI-EL-6800, Electric Power Research Institute, Palo Alto, CA, USA
Lee SH, Chung CK (2005) An experimental study of the interaction of vertical loaded pile groups in sand. Canadian Geotechnical Journal 42(5):1485–1493, DOI: https://doi.org/10.1139/105-068
Liang FY, Chen LZ, Shi XG (2003) Numerical analysis of composite piled raft with cushion subjected to vertical load. Computers and Geotechnics 30(6):443–453
Matsumoto T, Nemoto H, Mikami H, Yaegahi K, Arai T, Kitiyodom (2010) Load tests of piled raft models with different pile head connection conditions and their analyses. Soils and Foundations. Japanese Society of Soil Mechanics and Foundation Engineering 50(1):63–81, DOI: https://doi.org/10.3208/sandf.50.63
Rasouli H, Fatahi B (2019) A novel cushioned piled raft foundation to protect buildings subjected to normal fault rupture. Computers and Geotechnics 106:228–248, DOI: https://doi.org/10.1016/j.compgeo.2018.11.002
Saeedi AA, Baziar MH, Rasouli H, Modarresi M, Shahnazari H (2015) Centrifuge modeling of non-connected piled raft system. International Journal of civil Engineering 13(2):114–123, DOI: https://doi.org/10.22068/IJCE.13.2.114
Seo YK, Lee HJ, Kim TH (2006) Numerical analysis of piled-raft foundation considering sand cushion effects. The sixteenth international offshore and polar engineering conference, May 28–June 2, San Francisco, CA, USA
Zheng JJ, Abusharar SW, Wang XZ (2008) Three-dimensional nonlinear finite element modeling of composite foundation formed by CFG-lime piles. Computers and Geotechnics 35(4):637–643, DOI: https://doi.org/10.1016/j.compgeo.2007.10.002
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
El Kamash, W., El Naggar, H., Nabil, M. et al. Optimizing the Unconnected Piled Raft Foundation for Soft Clay Soils: Numerical Study. KSCE J Civ Eng 24, 1095–1102 (2020). https://doi.org/10.1007/s12205-020-0567-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s12205-020-0567-3